Hydraulics + Hangtime
After you have equipped your car (or SUV) with Hydraulics (Level 1, 2, or 3 will work) pull up to another vehicle or a wall and hold the R1 button and move your Left Analog Stick up and down in a rhythmic fashion to get your car rocking up and down (not bouncing). If you are close enough to the obstacle in front of you, your car will shoot straight up into the air, sometimes doing outrageous flips and spins. Once airbourne, release all the buttons, and if your car has soared into the sky parallel with the ground, "Hangtime" points will start to add up, sometimes 400+ Not very purposeful, but rather hilarious to watch. At the very least, you are refilling your nitrous/racebreaker. *Works in Online mode also*
Pop a wheelie (or a reverse wheelie)
Once your vehicle's Hydraulics have been upgraded to Level 3, if you are in a rear-wheel-drive vehicle, get your front end to bounce continuosly by double tapping and then holding the R1 button (handbrake) and pushing up on the Left Analog Stick a few times. You should now be able to release the R1 button and your RWD car (or SUV) should continue to bounce its front end. Having your transmission set to manual for best results, rev your motor all the way up and then shift into 1st gear. If your timing was right, your car will surge forward and pop a wheelie at the same time. Using nitrous once you shift into 1st gear will give you better results and may allow you to shift gears a few times before your car's front end drops back to the ground. You may flip over backwards if you take off too fast. With a front-wheel-drive car, simply get the rear hydraulics of your car bouncing and use reverse to pop a wheelie going backwards. You may have to rock your car back and forth by switching between forward and reverse throttle, but with the right touch, your FWD car should be able to do this trick also (going backwards of course), even though much less dramatic compared to going forward in a RWD car. You can have your car flip over in reverse also, or it may stand on its nose. This is not very purposeful, besides having other players (online) wondering how you popped a wheelie off the line. Sometimes you can "jump" other cars using this glitch, but during a race, you probably will not have enough time to go through all the steps. Worth a few laughs at least, and as said before, will keep other players (online) wondering...