My favorite intentional crashes come from 2 tracks in particular...
Laguna Seca Raceway & Mid-Field Raceway.
For best results, do the following:
Laguna Seca:
Get in your 1881HP Escudo, and enter in the Professional/GT All Stars @ Laguna Seca race. It is best when the opposing field includes the R390 and/or 787B.
Start the race backwards, going the wrong way to the Corkscrew (don't even cross the start/finish line). While still facing the wrong way (down the not-so-steep hill), wait for the leader to get about half-way along the straight that leads into the curve under the bridge (just before T2).
At this point, floor the gas and head down the hill, keeping the left side of your car in the center of the road (stay a bit to the right). As you go under the banner, line up the target for a head-on collision, and laugh your gas off as you see him fly 30 feet in the air (often into other vehicles).
Mid-Field Raceway (not M-F R II):
Get in your 1881HP Escudo, and enter in the Professional/Formula GT @ Mid-Field Raceway. Again, start the race backwards until you come to the end of the tunnel hairpin. Stop the car and wait for the leader to begin his looping left turn (which leads to the straightaway for T2). Floor the sucker and stay to the left, about a full car's width from the rumble strip.
As you cross the banner, you'll pick up one or two potential targets, which will send YOU in the air... as high as the banner.
Don't forget to buckle up!
Hazzard