I've managed it twice too, once with shields + turbo (I cannot say if I just got a normal speed boost or if it was thanks to the quake-surfing even faster than a normal bosst, but it looked really fast and cool) and once just with a turbo and without shields. I think it was a little slower than a normal speed boost on a straight, but thanks to the surfing it didn't stop me, it didn't changed the direction I was flying in and the engine "stopped burning" before the turbo lost his whole energy, but after the quake normally hits you, slows you down and presses you against the wall. So i hadn't to waste time with acclerating and could continue flying nearly as nothin happened.
It's defintely impossible to surf a quake deliberately, the precise moment is not distinguishable if you aren't a robot (or a Wellington). I surfed the quake both times accidentally, because I normally turn the game sounds down and my music to the maximum, so I hardly ever hear the warnings...
I have a question too: I raced some weeks ago a guy with a flag I have never seen before, maybe you guys know, where he was from. The flag was similar to the US flag but it was red and the left upper corner was blue. In the middle of the blue part there was a white, quite round, thing I couldn't identify because of the small size of the flags in the lobby. Here's a painting I made in MS Paint, I replaced the white thing with a white ball, maybe someone knows the flag: