Wow. A 6.5L diesel with 20 hp and 40 lbs-ft more. And a four speed transmission. These are significant changes.

The HUMMER now moves nicely around town. While the 6.2 was not bad, the 6.5 makes a difference. The extra power allows equal acceleration without as much drama. However, on the highway is the big difference. 4th gear really lowers the rpms and the motor no longer screams at you. In a 6.2 with a 3 speed, 65 is the limit with 60 being much more practical. 4th gear really drops the rpms down and can cruise at 65 all day without a problem. With the 6.5 you actually have some power left to push 70 or 75 (not recommended). You still have to downshift and slow down for the big grades but at least every grade is no longer a big grade!

The truck shifts into 4th pretty soon under low-moderate throttle, maybe around 30. The TC locks up at around 40, locking and unlocking in rolling terrain. In more hilly terrain, it will hunt around and 3rd gear should be selected (also for towing).

Sound levels are about the same around town. On the highway it's hard to tell because of 4th gear. Of course it is much quieter. Handling is still the same.

The interior is a little neater looking but not really that different. The faces on the gauges are different. The ability to move the passenger seat will be welcome to many cramped co-pilots. Taller drivers will also enjoy the extra leg room.

The new one piece runflat should solve many of the balancing problems and mechanics will enjoy the easier assembly. The rim itself is the same along with the tires. Externally the HUMMER is still so handsome in an ugly duck way.