I was looking at a few digi-meters last night at Sears. Basicly, I know I need DC for an auto, amperage is tested by the field around the wire and the shit that kills you, and you may be able to test some grounding issues with continuity.
What kind of meters do you like?
Is 400V enough coverage?
Do I need 400A?
Is there a Auto Electrics for Dummies edition?