Diesel engine as generator

Not if the engine is just used for a brief period of time and then shut down. A diesel engine would also add to the already big price tag. It would be great if you were running long stretches of highway like a train but then why not just have a straight diesel engine? Trains run at a steady speed for a long time. A car starts and stops rapidly and the way the Volt is set up, I'll bet many people would use the engine for just a few minutes before getting home. The diesel engine would never even warm up.

^^^ This is why. Plus, GM doesn't have a small diesel engine ready to go for a North American car. They have plenty of small fours ready. If the Volt is anything like the Prius they plan on losing money for many years before this technology pays off and I don't think GM is flush with cash...

You could say the same thing about the Prius, why not a diesel? The per unit cost is too high to put all that stuff into 1 car. It would be a good match though - diesel for generation and highway and the hybrid for city. The only drawback is that the diesel would take longer to warm up. I think Prius have a special insulated tank to keep the coolant hot.