Okay, I wasn't able to find the website I was thinking of. Damn, I wish I had saved the addy in my cache. Oh well. But after much searching I've found an obscure site called
http://jove.prohosting.com/~gtwo/ , and here's the text on wall bugs. Remember, mind you, that the other site I had found listed even MORE bugs than this one.
As for driving off of tracks altogether; it IS possible! I've had several emails, but this one pretty much sums it up best I think, so here it be!
At motorsportsland you should take the last turn before start/finish (180° left hander) entirely on the inside grass to get the "Wrong way" message. About half a second later you will see the "Off course" message. Proceed at racing speed and your lap time will not be registrated. Now continue trough the first turn and you will see most of the ground turns blue. Ignore the second turn (you can't see it anyway). Now you can drive straight trough the wall and test the car's ultimate top speed. This can be done with ANY car, including a standard Fiat 500R, if you want to test it.
At laguna seca it's a different story. There are two ways to go off course.
1) Near start/finish there ate two iron gates facing backwards. If you drive backward from the first turn and hit them full speed in the left corner, you can go trough one of them (don't remember which one). It takes some steering effort (left to right and vice verca) and full power to get trough it with a 4WD with 600+ HP or a Jag 220.
2) at the first turn you see a crash barrier with a wall of tires in front of it. If you hit the crash barrier at he point where the tire wall begins (right side of tire wall) and swerve a little with the steering, you can go trough there. If you notice that the car is IN the tire wall, you're getting close to going trough the crash barrier. Keep it near the place where you hit the wall, and you will eventually get trough. Also for high powered cars only.
Just for fun: If you go off course al Laguna, keep following the track but don't drive too close to it. It's easy to get back on course. You can keep off course all around the track, but it's fun to re-enter at the corkscrew. The track goes up, but your car keeps at the height of the first corner. When you re-enter at the corkscrew, the car will take a steep climb before making an enormous jump onto the track. We' ve tried it in two-player mode and I could see my opponent's Escudo suddenly coming up trough the tarmac 6 feet in front of my car and jumping about 20 foot high. Real fun! It is hard to orientate while off course, but luckily you can use the map ( in single player mode only) to see where you are and where you are going, because your car is still visible on the map.
At seattle, you can use the left-hand corner of the first turn for the same purpose (but it's hard to get it right) and re-enter with a huge jump at the highest point of the track ( 90° right-hander after the jumpy uphill section).
