Increasing gas prices (we hit $2.49/gallon on Friday) are starting to take their toll on used-truck prices. Used SUV trade-in prices have dropped approximately 5% in the past year, according to Edmunds, while the average value of used compact cars is 14% higher than a year ago. Wow. I wouldn't neglect the impact of the steep new-truck discounting, either; it's hard for many people to justify spending $20,000+ for a used late-model SUV or pickup when the GM dealer has 3/4-ton crew-cab pickups for under $30K. Even trucks with diesel powerplants are taking a hit, with Edmunds showing that a Duramax/Allison combo adds only $2700 to the private-party value of a 2002 Silverado 2500HD (that option carried a sticker price of over $7000). On the flip side, used compact car prices have increased 14.2 percent from last year.