There's a very easy glitch that will make cars go faster than their usual top speed. Simply charge a ram to its maximum strength, release the ram button, shift away from the vehicle, and then immediately back in a split second later. This makes the car you're in surge forward like doing a normal ram but will not suffer the missed-ram penalty. What I mean by missed-ram penalty is a sharp decline in speed if you release a ram and fail to collide with another vehicle. This glitch allows for a vehicle to reach its top speed very quickly and go faster than its top speed, if only for a brief second or two. However the time it takes your car to slow from maximum ramming speed is long enough for you to quickly execute the glitch again and keep a vehicle traveling significantly faster than simple boosting. This 'new' top speed scales to each vehicle, so sad to say you can't get a 200 mph semi truck. But the 180 mph Escalade that is possible can accomplish similar smashy-type results.
Once more from the top: Charge a ram to max Release the ram Immediately after release, shift away from the car Shift back into it again for lulz and win