Sometimes you just need to tow, say, a 5400-pound SeaRay boat on its trailer. Until now, it was impossible to do that in a hybrid--or, for that matter, in a pickup truck that gets more than 20 miles per gallon.

Enter the newest in GM's expanding lineup of Two-Mode Hybrids: two full-size pickup trucks. The 2009 Chevrolet Silverado Hybrid and its all-but-identical twin, the 2009 GMC Sierra Hybrid, are now reaching dealers. And their 2WD versions sport that all-important statistic for full-size pickups: The ability to tow up to 6100 pounds while still returning 21 mpg (city) / 22 mpg (highway).

Hah, you scoff; how can 22 mpg possibly be green? Well, consider that the non-hybrid version of that same truck returns just 14 mpg / 20 mpg. So if you do 10,000 miles a year, half in the city and half in the country, you're saving about 140 gallons of gasoline a year. (Yes, your mileage may vary.)

Not very impressive, you say: The hybrid powertrain adds roughly $3,000 over the cost of the closest comparable non-hybrid pickup truck. So that's more than a 10-year payback at $2 a gallon.

True, but these trucks also come with a $2,200 tax credit, at least until GM's credits expire (as those for Toyota and Honda already have; Ford credits are almost gone too). All of a sudden, your payback is down to 4 years--less if you use your truck in mostly urban settings.

We'll have a drive report in a day or two. Meanwhile, be aware that the hybrid option is only offered with a four-door Crew Cab body (the most popular format, with roughly a 45-percent share of GM's pickup sales) and a 6.0-liter V8. There are two trim levels; standard and luxury, which adds leather seats and a variety of other appointments to make your loading, hauling, and trucking that much more comfortable.

You can choose 2WD or 4WD, and and specify a handful of options like a sunroof. Due to the added weight of its drivetrain, the hybrid pickup with 4WD has slightly lower towing ability (5900 pounds) and mileage (20 city, 20 highway).

Pricing for a 2009 Chevrolet Silverado 1500 2WD Crew Cab Hybrid with the luxury package starts at $44,155; a 2009 GMC Sierrra 4WD Hybrid, also in the high-line model, runs $47,675.

2009 Chevrolet Silverado Hybrid - dashboard

2009 Chevrolet Silverado Hybrid - dashboard