We just got word of the latest GM FastLane Blog podcast, and in it Bob Lutz doesn't appear to be too keen on diesels. While admitting that GM is working on diesel powerplants for use in passenger vehicles sold in the U.S., he tries to emphasize the fact that diesels aren't a cure-all. Lutz sees only a 12-15% benefit to diesels over gas engines in fuel mileage given the stricter emissions standards for diesels that are now in place. With the new Bin 5 Tier II standards (not to mention the even stricter standards set by the California Air Resources Board) on the horizon, he thinks a diesel-powered car will cost $2,000 to $2,800 more than a gas-powered one because of extra emissions hardware, and that's on top of the $1,000 to $2,000 premium for diesels to begin with.

His bottom line seems to be that diesels can be better than gas engines for mileage, but that the added cost to meet new emissions standards are making them less attractive. While we've been heartened to see the promise of more diesels coming to the States, it's true that they don't really answer all of the concerns about a diminishing crude supply, nor the environmental impact of automobiles. They may reduce our use of crude, but there are costs associated with them that make them a temporary step at best. Renewable energy sources are a better option ultimately, but for the time being, diesels can help us reduce our dependency. It might sound like sour grapes a bit coming from Bob's lips, but he has a point. Click play and watch his thoughts on this issue for yourself.