Not completely impossible.
Take the XRGT. Now go to the car selection and select the XRGT Turbo. You just put a spoiler on the back of your car and engine hopups in the form of a turbo. Now, go to
www.liveforspeed.net, buy a license, and go back to the car selection. Select the XR GTR. It has more engine hopups bringing the HP up to 400 or so and a front and rear actual wing creating downforce compared to the normal XRGT and XRGT Turbo.
Have fun
.