What do D+ and D- mean in cars?

[VanStephen]

Automatic transmission D+ or D- means the ability to freely shift down gears, allowing high-performance sports cars to break free from the constraints of traditional automatic transmissions and enabling drivers to enjoy the fun of manual shifting. Below is an introduction to automatic transmissions: Automatic Principle: The engine's power is transmitted through the gearbox, which is also a key factor affecting fuel consumption. Generally, automatic transmissions consume over 10% more fuel than manual transmissions. Whether manual or automatic, the more gears a transmission has, the more fuel-efficient it is. Driving Tips: For manual transmission cars, it is recommended to shift up at higher RPMs. Engines are designed to operate at higher RPMs, with various components' dynamic balance and rotational inertia parameters also designed based on high RPMs. If the engine operates for extended periods outside its normal working range, internal component load and wear naturally increase, leading to frequent vibrations and knocking, which can affect lifespan. Choosing 3000 RPM as the shift-up point ensures that after shifting, the engine operates at around 2300 RPM, keeping it within a healthy RPM range.