Vehicle Overview
Even after the new and smaller Hummer H2 arrived in 2003, the original Hummer H1 continued to capture attention. The H1 is the most noticeable and forbidding of all the sport utility vehicles on sale. It's considered by many to be the toughest SUV, whether it's rumbling down a paved road or through the most demanding offroad trek. The manufacturer bills the H1 as "the world's premier offroad vehicle, rugged enough for Baja, refined enough for the country club." No H1s were produced in 2005.

After a yearlong hiatus, the 2006 H1 becomes the H1 Alpha. It's been extensively revised, with a new 6.6-liter turbo-diesel V-8 replacing the previous 6.5-liter engine. This improved power plant offers significantly more horsepower and torque and uses a new five-speed-automatic transmission.

The H1 Alpha also features freshened styling and revised braking and suspension components. It sits 2 inches higher than the 2004 H1, though ground clearance remains the same.

The H1 Alpha comes as an open-top model and a four-door hardtop. Due to its weight, the H1 Alpha falls into a heavier-duty category than other SUVs and doesn't have to meet federal safety, emissions and fuel-economy requirements.

While the Hummer appears massive, versatility is one of its hallmarks. The overpowering H1 Alpha is easy to spot from a distance, with an overall length of 184.5 inches, a 130-inch wheelbase and a 71.6-inch track (the width between the wheels). Two fuel tanks that hold 29.5 gallons and 22 gallons are installed. Run-flat tires on 17-inch aluminum wheels are standard. A restyled brush guard, new wheels and various badges differentiate the H1 Alpha from previous H1s.

The H1 Alpha's 16-inch ground clearance is more than twice that of most SUVs. A 72-degree approach angle and a 37.5-degree departure angle intensify its climbing capabilities.

Four seats are spread around the perimeter of the interior. A massive center tunnel separates occupants inside. Despite its militarylike external appearance, the H1 Alpha offers an appealing selection of comfort and convenience features, including leather seats and air conditioning.

Under the Hood
For 2006, the H1 Alpha's new 6.6-liter turbo-diesel V-8 features aluminum cylinder heads and direct fuel injection. It makes 300 hp and a burly 520 pounds-feet of torque — a significant increase over the previous 6.5-liter engine's 205 hp and 440 pounds-feet. A new five-speed-automatic transmission replaces the previous four-speed unit and offers a tow/haul mode. A permanently engaged four-wheel-drive system has a Low range and a locking differential. Hummer claims the H1 can climb 60 percent grades.

Antilock brakes are standard. The H1 falls into a heavy-duty vehicle category, so airbags aren't required.