any car with his same powerband has same effect, they are plenty specially in cars that use mid range turbo, every car tune its different and every player has its own way to achieve the max performance on the car that is different from another player thus my cars don't give the best times but when match against a top time car my car outperform it with a even launch and most times if i got treed. GT5 lets you make it your own, my ways of tuning can't be explain but i try to give the closet to it advice so players get a basic idea.
There's more to a tune that what your eyes can see.