...or go the whole hog and report it as an Abandoned Vehicle.

Alternatively, next time the oil's changed in your car, tip a bit of it in a worrying puddle under his current car. For that extra-special visual effect, stir in a teaspoon of Crunched Metal Bits and swarf, available on the floor of any good automotive workshop.

If he doesn't notice (or doesn't care) the first couple of times, get some rubber tubing and squirt oil up his exhaust. Hint: the effect is delayed until the exhaust heats up, but make sure you don't have the washing out, in case he chooses that day to impress the street by sitting around and revving his engine.