the other day (Sunday) i went karting to a "fun event" - 1 hour 30 Endurance race, 2 types of karts, 240 CC's and 200 CC's (200's have been abused to hell). There was a mixture of quick people who knew the track, people who'd never been in a kart before, and Rob Huff (The WTCC driver - who lapped the whole field in 5 minutes!). The first time i went out, i went in the 240, did rather well, gained some places, the second time i went in the abused 200, which was constantly under attack by the faster 240's (on the exit of every turn that extra power really shew - and on the straight they could fly past if i let them
), so on the entry to a few corners (and the exits) i drifted it a bit - one time i had to overtake someone just before the entry to a corner (they were in a 240, but f*cked up the corner before and i got it perfectly (for once!)) - to stop them getting past on the apex i shifted the weight around and got it very sideways on the exit, they couldn't pass (my car was sideways next to the grass) without ramming me or hitting the grass, and had to let off, and as the next whole section was flat out they only managed to recoup the speed at the end.
I also used drifting to recover from getting VERY sideways (90 D0r1fT0 y0!) on a patch of water.
Its useful in SOME situations, and possible, but drifiting never made me quicker!