Cursor pointed out this Strib article on the possible declining interest in hummers among consumers. I work building the software and simulating virtual designs for big diesel rigs everyday and these humvees do not impress me in the least. Show me a cool road or mountain bike to get me excited.
Another more important potential interest is in hybrid diesels. I know for a fact that diesel ground vehicles up to 20-tons are being designed right now using hybrid-electric drives. What my colleagues and myself are finding is the huge space savings within the vehicle; because of the efficiencies in the powerplant, you get a counter-intuitive reduction in size.