Originally from www.dervman.com - the ultimate nerd site for the pursuit of utter pointlessness, now brought into generic use for any car driver whose quest for fuel economy (that's Gas Mileage for you seppos) overcomes any other requirement of praticality or enjoyment for a car.
Tends to either own a diesel driven car (DERV = DIESEL ENGINED ROAD VEHICLE) or spend all his time justifying the use of small petrol engines, silly air intake modifications, lean burn devices, ECU monitors etc.
He's nerdy enough to be a Dervman
If you buy the Mondeo you'll become a proper Dervman
Dervman will be happy - Alfa do diesels now.