The knowledge base of the AutoblogGreen readership is quite amazing, and I take great pride in the fact that almost all of the comments our readers leave are smart and useful. And, since you're all smarter than I am, I'd like to pick your brains about the best diesel truck or frugal SUV (the way you helped out before).

A friend of mine has gotten fed up with his F-250 and wants to replace it with something more nimble and maneuverable. He prefers a diesel, because he wants to use biodiesel when possible. Other requirements are that this truck be able to tow a boat, which is about 2,000 pounds, now and again and it not be crazy expensive ($20,000 or so would be great). Good mileage and low emissions obvious are pluses.

At this stage in his research, he's kind of leaning toward a 2006 Jeep Liberty Diesel. They're available used for around 20k and he's read that some people are using B100 in them just fine (and Jeep sold them with B5 in the tank). With user mileage reported to be in the 24-32 mpg range (which is more than some sources say), that's not too bad, considering he's likely to use this truck for his daily driver as well. He's ruled out a new Jeep Grand Cherokee as they're too expensive, and he'd like more information from people who have experience with the Commander. He's not locked into the Jeep brand, but it seems like they're offering what he's looking for.

So, what do you think he should get?

UPDATE: added SUV to title and story, instead of just truck.