[texanidiot25]

That's not exactly how it works. The gear selector just tells what is the highest gear the car will shift into. It will still down shift the same as before.

Imagine on my car for instance, it's 1, 2, D, and (D) (over drive, 4th gear). If I were to shift it from 1st to D (3rd on your car) while still accelerating hard, the car will still shift into 2nd, and then into 3rd, and then no higher. It's not like your forcing the trans to upshift on your own accord, it will still up shift as normal until it hits what ever gear you have selected, and then it sticks there.

The real use you would have it to hold the RPMs higher at part throttle then the auto would normally for some spirited/performance driving that has many up/down shifts and you want the engine to stay revved up, and also allow the car to engine brake when off the trottle (auto-X).

But for regular driving, and drag racing even, just keep it in D and let the auto do it's job. Their already programed to stay in the highest gear it can for economy.

Although if your really determined, you can convert an automatic to manual shift. Where the gear selector alone will change the gears, not the tranny itself. A lot of drag racing transmissions are set up like this. With this setup, you can even start off the line in a higher gear, not 1st like an auto does..