What are the main differences between the Audi A8 L, Audi A8 TFSI, and Audi A8 TDI?

I am looking to purchase an Audi A8 and I am confused about the different trim levels available. Can you explain the main differences between the Audi A8 L, Audi A8 TFSI, and Audi A8 TDI in terms of performance, features, and price?

The Audi A8 L stands for long wheelbase, giving you extra legroom and comfort in the backseat. The TFSI stands for turbocharged fuel stratified injection, offering a powerful and efficient gasoline engine option. The TDI stands for turbocharged direct injection, offering a diesel engine option for even better fuel economy. In terms of performance, the A8 L and TFSI have similar specs, but the TDI has a lower horsepower and torque. However, the TDI makes up for it with better fuel efficiency. Additionally, the A8 L has more luxury features standard than the TFSI and TDI, making it the most expensive option overall.