Electric cars do not have transmissions in the same way that gasoline-powered cars do. This is because electric motors provide torque throughout their speed range, while gasoline engines only provide good torque within a limited RPM range. However, some electric cars do still have gearboxes and need transmission fluid, just for different reasons than a standard transmission.
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Why Electric Cars Don’t Need Transmissions
In a gasoline-powered car, the engine only provides good acceleration and torque within a certain RPM range. To keep the engine in this optimal range as the car speeds up, a transmission is needed. The transmission allows the engine to spin faster while the wheels spin slower by providing different gear ratios. Without a transmission, the engine would bog down at low speeds and scream at high speeds.
Electric motors work very differently. They provide maximum torque from a stop and maintain it across their entire speed range. This allows them to accelerate smoothly from 0 rpm up to extremely high speeds. They do not have a narrow power band like a gas engine. This characteristic of electric motors eliminates the need for a transmission just to keep them in their optimal operating range.
Gear Reduction for Improved Efficiency
While they don’t require a transmission, some electric cars do employ a single speed gear reduction unit between the motor and wheels. This helps improve efficiency and allows the motor to spin faster while the wheels spin slower.
Spinning motors faster reduces the amount of current they need to produce the same power output. This improves efficiency. The gear reduction allows the motor to spin faster internally while the wheels spin at normal highway speeds. It provides some of the benefits of a transmission without the complexity.
Why Some EVs Have Multi-Speed Gearboxes
While they don’t require complex multi-speed gearboxes, some electric cars do utilize them. There are a few reasons an automaker may choose to include a multi-speed transmission in an EV:
- Improving acceleration – Having multiple gears allows better acceleration from a stop by starting out in a low gear.
- Increasing top speed – Higher gears allow EVs to reach higher top speeds which some customers desire.
- Maximizing efficiency – The optimal motor speed for efficiency varies, so multiple gears allows the motor to stay in its sweet spot.
- Maintaining motor longevity – Keeping the motor from spinning too fast reduces wear and increases lifespan.
So while they aren’t required like in gas cars, gearboxes do still provide some benefits in electric vehicles in the right applications.
EVs With Multi-Speed Transmissions
Some examples of electric vehicles that use multi-speed gearboxes and transmission fluid include:
Tesla Roadster
The Tesla Roadster uses a proprietary 2-speed transmission in addition to its electric motor. It allows the motor to reach optimal efficiency at both lower and higher speed ranges. Shifting gears changes the speed ratio between the motor and wheels.
Porsche Taycan
The Porsche Taycan has a unique 2-speed transmission on its rear motor. First gear provides rapid acceleration from 0-60 mph. Second gear is optimized for efficiency at higher speeds. Porsche utilizes transmission fluid to lubricate the gears.
Audi e-tron GT
The Audi e-tron GT uses a 2-speed transmission on the rear motor to improve 0-60 mph times and provide efficient high-speed cruising. The transmission requires dedicated transmission fluid.
Lucid Air
The Lucid Air utilizes a compact 2-speed transmission on its rear motor. The automaker says the gearbox improves efficiency, performance, and driver comfort compared to a single speed drive. Transmission fluid lubricates the gears.
Rivian R1T
The Rivian R1T pickup uses a 2-speed gearbox on its rear motor to optimize performance and efficiency across the speed range. Rivian recommends inspecting the transmission fluid at regular service intervals.
Do EVs With Gearboxes Require Fluid Changes?
For electric vehicles equipped with multi-speed gearboxes, transmission fluid changes are required periodically just like a standard transmission. The fluid lubricates the gears and prevents wear. It also needs to be changed to remove any accumulated metal shavings caused by gear wear over time.
The service interval varies by vehicle, but is generally between 30,000-60,000 miles. Refer to the maintenance schedule in your owner’s manual. Some automakers may call for “inspection” of the fluid at shorter intervals to check condition.
Many EVs have sealed transmission units that never need fluid changes. But for those with exposed fill plugs, changes at the specified intervals are important. Use only the transmission fluid specified by the manufacturer.
Signs Your EV’s Transmission Needs Service
Some signs your electric vehicle’s transmission may need service include:
- Noisy operation or gear whine
- Difficult/delayed gear shifting
- Leaking fluid
- Burnt smelling fluid
- Fluid that appears cloudy or contaminated
- Transmission slipping
Schedule an inspection if you notice any of these symptoms. Worn transmission fluid can lead to bigger problems if not addressed promptly.
Conclusion
While electric vehicles do not require complex transmissions like gas-powered cars, some do still utilize multi-speed gearboxes. This provides performance and efficiency benefits. EVs with exposed transmission fluid need periodic fluid changes and service just like a standard transmission.
Signs your EV’s transmission needs attention include shifting delays, leaks, noise, or slipping. Poor maintenance can lead to expensive repairs down the road. Follow your manufacturer’s recommendations for inspecting or changing transmission fluid at the specified intervals.