What Is an Automatic Car Transmission?
Cars with automatic transmissions are now available across many segments, from city cars and LCGCs to MPVs, SUVs, hybrids, and electric vehicles. To illustrate the size of Indonesia’s vehicle market, GAIKINDO recorded retail car sales of 833,692 units throughout 2025. Consumers can also find a wide range of automatic transmission technologies today, including conventional AT and CVT systems across different price ranges and vehicle segments.
An automatic car transmission is a transmission system that changes drive ratios without requiring the driver to operate a clutch pedal or shift gears manually as in a conventional manual transmission. The system adjusts the ratio according to driving conditions such as vehicle speed, engine load, accelerator position, and other parameters read by the vehicle’s control system.
In an automatic car, the driver generally only needs to operate the accelerator and brake pedals. The transmission lever or selector usually includes P (Park), R (Reverse), N (Neutral), and D (Drive). Some vehicles also provide additional positions or modes such as S, L, B, or a manual mode, depending on the transmission type and the manufacturer’s design.
However, the term “automatic car” does not refer to a single technology. Although these systems share the convenience of not requiring a clutch pedal, they include technologies such as Automatic Transmission (AT), Continuously Variable Transmission (CVT), Dual-Clutch Transmission (DCT), Automated Manual Transmission (AMT), and e-CVT. Their different mechanisms can result in different acceleration characteristics, power delivery, fuel efficiency, and maintenance requirements.
How Does an Automatic Car Transmission Work?
Simply put, a transmission transfers power from the power source to the wheels while regulating the relationship between rotational speed and torque. The aim is to deliver the appropriate amount of power to the wheels for specific driving conditions.
In a conventional automatic transmission or AT, the system generally uses key components such as a torque converter, planetary gear set, clutches, brakes, and hydraulic and electronic control systems. The torque converter transfers engine power to the transmission, while the planetary gear set enables multiple gear ratios.
When the vehicle begins moving, the transmission uses an appropriate ratio to produce the required torque. As speed increases, the transmission can shift to a higher ratio so engine speed can be adjusted to suit driving conditions.
In modern cars, this process is largely controlled electronically through a Transmission Control Module (TCM) or a control system integrated with the Electronic Control Unit (ECU). The system reads information such as vehicle speed, engine speed, throttle position, and engine load, then determines the appropriate ratio-shifting strategy.
However, this mechanism is not the same in every automatic car. A CVT, for example, uses continuously variable ratios rather than fixed gear steps like a conventional AT. A DCT uses two clutches to manage different groups of gears alternately. Because the mechanisms differ, each transmission type can also provide a different driving feel.
Common Automatic Transmission Selector Positions
Position
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Function
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P – Park
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Used when the vehicle is parked. In many automatic transmissions, P engages a parking pawl mechanism that helps lock the transmission. Continue to use the parking brake as instructed by the vehicle manufacturer.
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R – Reverse
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Used to move the vehicle in reverse. Shift to R only after the vehicle has come to a complete stop.
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N – Neutral
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The transmission is in neutral, so drive power is not transmitted to propel the wheels. Use it according to the situation and the manufacturer’s instructions.
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D – Drive
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The main position for driving forward. The system automatically adjusts transmission ratios according to driving conditions.
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S – Sport
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On certain vehicles, this mode changes transmission response for a sportier feel, for example by holding higher engine speeds.
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L – Low
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On certain vehicles, this position maintains a lower ratio and can help in conditions requiring more torque or stronger engine braking.
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B – Brake
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Found on some hybrid or electrified vehicles. Its function depends on the vehicle system and may be used to increase deceleration, engine braking, or regenerative braking.
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Disclaimer: The arrangement and functions of transmission positions may vary by brand, model, and transmission technology. Not every automatic car has S, L, or B modes, and some modern cars use buttons, dials, or electronic gear selectors instead of a conventional lever. Always refer to the vehicle owner’s manual for the correct function and use of each transmission position.
Types of Automatic Car Transmissions
The term “automatic car” actually covers several transmission technologies with different mechanisms. Some systems use a torque converter, others use continuously variable ratios, some use two clutches, while electrified systems may manage power from both an engine and an electric motor.
These differences in construction affect how power is delivered to the wheels, acceleration feel, efficiency, and maintenance requirements. Below are several types of automatic transmissions commonly found in modern vehicles.
Type
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How It Works
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Characteristics
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Notes
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1. Conventional Automatic Transmission (AT)
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Generally uses a torque converter and planetary gear set. Ratio changes are achieved through combinations of clutches and brakes controlled hydraulically and electronically.
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Gear changes occur in distinct steps and generally feel familiar to many drivers.
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Modern ATs can have many gear ratios and a lock-up system to help reduce power losses.
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2. Continuously Variable Transmission (CVT)
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Generally uses two pulleys with variable effective diameters and a belt or chain to provide a continuous range of ratios.
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Acceleration tends to be smooth because it does not rely on shifts between fixed gears like a conventional AT.
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Under strong acceleration, engine speed may rise and remain at a certain RPM, creating a different feel from an AT.
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3. Dual-Clutch Transmission (DCT)
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Uses two clutches that generally control odd and even gear groups. The system can prepare the next gear before the shift takes place.
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Gear changes can be fast and responsive.
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Available in wet-clutch and dry-clutch configurations. Its behaviour when creeping or in stop-and-go traffic can differ from a torque-converter AT.
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4. Automated Manual Transmission (AMT)
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Essentially uses a manual-transmission design, but actuators take over clutch operation and gear changes.
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No clutch pedal is required, although gear changes may feel more noticeable than with some other automatic transmission types.
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Because it uses the basic mechanism of a manual transmission, its power-delivery characteristics differ from a conventional AT.
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5. e-CVT in Hybrid Vehicles
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In some hybrid systems, power from the engine and motor-generator is divided through a power-split mechanism that may use a planetary gear set.
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Power delivery feels smooth, and the system can automatically manage the contribution of the engine and electric motor.
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e-CVT terminology and construction can vary between manufacturers. An e-CVT in a power-split hybrid system is not the same as a pulley-and-belt CVT.
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Disclaimer: Technology names used by manufacturers do not always indicate the same construction. For example, CVT and e-CVT should not be considered identical technologies simply because both use the term CVT. Check the vehicle’s technical specifications to determine the actual transmission type used.
Differences Between AT, CVT, DCT, AMT, and e-CVT
No single transmission type has exactly the same characteristics across all vehicles. Software calibration, engine output, vehicle weight, number of ratios, and hybrid-system configuration can all influence the driving experience.
In general, the differences can be seen below.
Type
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Main Mechanism
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General Characteristics
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Commonly Used For
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AT
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Torque converter + planetary gear set
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Stepped gear changes with generally smooth characteristics
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A wide range of everyday driving needs, both in and out of the city
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CVT
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Pulley + belt/chain
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Continuous ratio changes and generally smooth acceleration
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Vehicles prioritising smooth driving and efficiency
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DCT
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Two clutches + gear set
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Fast and responsive gear changes
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Vehicles prioritising responsive gear changes
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AMT
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Manual transmission + automatic actuators
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Gear changes may feel more noticeable
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Certain vehicles using a manual-transmission-based design with automated operation
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e-CVT
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Depends on the hybrid system; some use a power-split device and motor-generator
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Smooth and integrated with the electrified system
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Certain hybrid vehicles
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Disclaimer: The table above describes general characteristics rather than absolute rules. Two cars with the same transmission type can provide different driving experiences because of differences in design, calibration, engine, electric motor, weight, and technology.
Advantages and Considerations of Automatic Cars
One reason many people choose automatic cars is their ease of operation. Drivers do not need to repeatedly operate a clutch pedal and shift gears as they would in a manual car. Even so, automatic cars still have characteristics and operating requirements that drivers should understand.
Aspect
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Advantages
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Points to Consider
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Ease of Driving
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No need to operate a clutch pedal or shift gears manually during normal driving.
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Drivers still need to understand P, R, N, D, and any additional available modes.
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Heavy Traffic
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More practical when the vehicle frequently stops and starts.
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Smooth accelerator and brake control is still needed, especially when creeping.
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Comfort
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The system manages ratio changes without requiring the driver to shift gears manually.
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Smoothness varies between AT, CVT, DCT, AMT, and other technologies.
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Efficiency
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Modern transmissions can select or adjust ratios according to driving conditions.
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Fuel consumption is not determined by transmission type alone. The engine, vehicle weight, tyres, road conditions, and driving style also have an effect.
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Maintenance
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Drivers do not need to operate a manual clutch as they would in a manual car.
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The transmission still has components and fluids that must be inspected or maintained according to manufacturer requirements.
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Disclaimer: Automatic cars are not necessarily more fuel-efficient or less fuel-efficient than manual cars. Efficiency should be compared based on the vehicle model and its overall configuration, rather than solely on the type of transmission.
How to Use an Automatic Car Properly
Although operation is relatively simple, several habits can help ensure the transmission is used as intended by the vehicle’s design.
Habit
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Explanation
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Press the Brake When Selecting a Transmission Position
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When shifting from P to R or D, follow the vehicle procedure and press the brake pedal before selecting the transmission position.
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Stop Before Changing Direction
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Avoid shifting from D to R or R to D while the vehicle is still moving in the opposite direction. Wait until the vehicle has stopped first.
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Use the Parking Brake When Parking
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P uses a transmission mechanism to help hold the vehicle, but you should still use the parking brake according to the vehicle procedure, especially on an incline.
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Do Not Hold the Vehicle on an Incline Using Only the Accelerator
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Use the brake pedal, electronic parking brake, Auto Hold, or hill-start assist according to the vehicle’s features and instructions.
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Understand Manual Mode or Paddle Shifters
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If available, these features can provide greater control over transmission ratios in certain conditions, such as when driving downhill.
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Avoid Selecting P While the Vehicle Is Still Moving
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Make sure the vehicle has stopped before selecting P because this position may engage a transmission locking mechanism.
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Follow the Correct Towing Procedure
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Do not assume all automatic cars can be towed in the same way. The driven wheels and transmission type determine the permitted towing method.
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Understand Special Modes
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S, L, B, M, and other modes can have different functions depending on the manufacturer. Use them according to the owner’s manual.
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Disclaimer: Transmission-selection procedures may differ between vehicles with mechanical levers, electronic shifters, shift-by-wire systems, hybrids, and electric vehicles. The owner’s manual remains the primary reference because some vehicles have their own safety procedures and operating sequences.
Automatic Transmission Maintenance
The transmission is one of the vehicle’s complex mechanical and electronic systems. Proper maintenance is not only about changing transmission fluid but also ensuring that the fluid, components, and control systems operate according to specification.
Maintenance
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What to Do
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Follow the Manufacturer’s Service Schedule
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Use the owner’s manual as the reference for inspection intervals and replacement of transmission components or fluids.
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Use the Correct Fluid Specification
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ATF, CVT fluid, DCT fluid, and other fluids have different formulations and specifications. Use the type recommended by the manufacturer.
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Monitor Fluid Condition
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If the vehicle provides a fluid-check procedure, monitor its condition and level according to the manufacturer’s instructions.
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Watch for Unusual Symptoms
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Unusual jolts, slipping, delayed gear engagement, vibration, abnormal noises, or warning lights should be checked.
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Check for Possible Leaks
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Seepage or drops of fluid beneath the vehicle may indicate a leak and should be inspected.
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Do Not Delay Inspection
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Symptoms that initially seem minor can worsen if the cause is not identified promptly.
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Use a Workshop Familiar with the Transmission Type
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Diagnosing AT, CVT, DCT, and hybrid systems may require different procedures, diagnostic equipment, and technical expertise.
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Disclaimer: Avoid applying a universal rule such as “transmission fluid must be replaced every certain number of kilometres” to every automatic car. Service intervals, replacement methods, fluid types, and inspection procedures may vary depending on the vehicle model and operating conditions. Follow the owner’s manual and manufacturer recommendations.
Signs of Automatic Transmission Problems
A change in transmission behaviour does not always indicate serious damage. However, symptoms that recur, worsen, or differ significantly from the vehicle’s normal characteristics should not be ignored.
Symptom
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Possible Areas to Check
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What to Do
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Shifts Feel Jerky
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It may be related to fluid condition, the control system, actuators, internal components, or other causes.
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Have it checked if the jolting occurs repeatedly or differs from the vehicle’s normal behaviour.
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Delayed Engagement of D or R
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It may be related to hydraulic pressure, fluid, electronic controls, or transmission components.
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Have the vehicle inspected if there is an unusual delay after selecting D or R.
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RPM Rises but Acceleration Does Not Match
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On certain transmissions this may indicate slipping, but normal CVT characteristics should also be considered during diagnosis.
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Avoid diagnosing the cause yourself and have it inspected if the symptom appears abnormal.
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Unusual Vibration or Noise
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The source may be the transmission or another vehicle component.
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Have the vehicle diagnosed to determine the source of the vibration or noise.
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Burning Smell
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It may be related to overheating or certain fluids/components, but the source of the smell needs to be confirmed.
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Stop using the vehicle if the condition feels unsafe and have it inspected.
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Fluid Leak
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It may indicate a problem with a seal, gasket, connection, or another part of the system.
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Check the source of the leak and the fluid level according to the vehicle procedure.
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Warning Light Comes On
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The ECU or TCM may detect an abnormal condition in the transmission or powertrain system.
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Check the owner’s manual and have the vehicle diagnosed using the appropriate procedure.
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Transmission Enters Fail-Safe Mode
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Some vehicles have a fail-safe or limp mode that limits operation when the system detects certain faults.
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Avoid forcing the vehicle to continue operating and arrange an inspection as soon as possible.
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Disclaimer: The symptoms above cannot be used as a definitive diagnosis. For example, rising RPM during acceleration does not necessarily mean a CVT is slipping, because a CVT can normally hold engine speed within a certain range. Diagnosis should be based on symptoms, fault codes, fluid condition, electronic checks, and mechanical inspection by a technician.
Tips for Choosing an Automatic Car for Your Needs
Choosing an automatic car should not be based solely on its transmission type. Two cars that both use a CVT or AT, for example, may still have different driving characteristics. Transmission calibration, engine output, vehicle weight, safety features, and everyday use all influence comfort.
Before buying, consider the routes you drive most often, the number of passengers, how frequently the car will be used, maintenance costs, and the availability of after-sales service.
Need
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What to Consider
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For City Driving
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Consider smoothness when starting and creeping, accelerator response at low speeds, fuel consumption, and comfort in stop-and-go traffic.
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For Out-of-Town Trips
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Consider response when accelerating to overtake, stability at higher speeds, engine-braking capability, and the availability of a manual mode if needed.
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For Families
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Do not consider the transmission alone. Look at cabin capacity, passenger comfort, safety features, luggage space, fuel consumption, and ease of operation.
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For Drivers Who Prefer Responsive Performance
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A DCT or fast-shifting AT may be an option. Consider kickdown response, gear changes, and the availability of Sport mode or paddle shifters if those features are important to you.
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For Hybrid Cars
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Understand how the hybrid system works as a whole. In certain vehicles, the e-CVT is part of the system that distributes power between the engine and electric motor and differs from a conventional pulley-and-belt CVT.
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For Long-Term Ownership
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Check the service schedule, fluid type, vehicle and transmission-component warranties, routine maintenance costs, and the availability of workshops and spare parts.
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For Used Automatic Cars
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Check the service history, response when selecting D and R, transmission condition when cold and after use, leaks, unusual noises or vibrations, and warning lights on the instrument panel.
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Disclaimer: Do not make a decision based only on the assumption that one transmission technology is always better than another. A test drive is important for experiencing the vehicle’s characteristics directly. Where conditions allow, try the vehicle in situations similar to everyday use, including starting, stopping, creeping, climbing, and accelerating.
Automatic Cars Need the Right Protection
The transmission type is not the main factor in determining whether a car should be insured. The considerations are broader, ranging from the vehicle’s value and frequency of use to environmental conditions and the financial risks that may arise from unexpected events.
Automatic cars can still face various risks during ownership and use, including collisions, accidents, theft, fire, and certain risks arising from natural disasters. Therefore, in addition to regular transmission and vehicle maintenance, car owners can consider Oona Car Insurance as part of their vehicle protection.
Oona Car Insurance offers Comprehensive and Total Loss Only (TLO) protection options that can be selected according to your vehicle protection needs.
Type of Coverage
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Overview
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Comprehensive
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Provides protection against partial damage as well as total damage or loss resulting from risks covered under the policy.
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Total Loss Only (TLO)
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Provides protection when damage meets the policy’s criteria for a total loss or when the vehicle is lost due to a covered risk.
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Disclaimer: The term “All Risk” is often used to refer to Comprehensive coverage, but it does not mean that every possible type of damage is covered. Coverage, exclusions, deductibles, optional extensions, and claim terms remain subject to the applicable policy.
Keep in mind that car insurance is not a substitute for routine maintenance or the vehicle warranty. Mechanical transmission damage caused by wear and tear, component age, or inadequate maintenance is not automatically covered by insurance.
When choosing protection, do not consider the premium alone. Also review the covered risks, exclusions, sum insured, deductible, partner repair shops, claim procedures, and optional coverage extensions. Protection against risks such as flooding and certain natural disasters, for example, may require additional coverage depending on the product and policy terms.
With the right protection, you can be better prepared for financial risks arising from unexpected events while owning and using your car. Learn more about Oona Car Insurance and choose coverage that suits your vehicle’s needs.
