Yeah, its much harder to get away with that now unless your car is exempt from MOTs (yes that's Taxis!), an MOT test has to be hooked up to a computer and the results recorded live (for emissions tests I think)
There is a garage less than half a mile away from where I'm sat right now that was notorious in the taxi trade. It was one of the few approved Taxi testing stations and as long as your car was semi-roadworthy, £20 left in the ashtray would secure a pass from the MOT tester. I don't even think the owners of the garage were aware of what he was up to but he was earning a fortune - 4 tests an hour, 8 hours a day, 5 days a week. A good 80% of their trade was taxis. The flipside was also if you didn't leave £20, your car had better be 100% perfect or it was failing