The 2008 GL320 CDI is the best MB I've yet owned, out of 4 different models. It is my go-to car for all short errands and long trips. It is very comfortable, super quiet, safe, has excellent pickup (we live in the hills), has great visability and gets good mileage - averaging 20 mpg city / hwy. Also, in my mind, diesels are a better environmental solution than hybrids because of the battery production and disposal issue. Few vehicles with this weight have the same ability to pass other vehicles when you are going 40 mph or faster. We have towed horses and hardly notice the additional weight except for more downshifting and fuel consumption.
Unexpected great feature in Texas heat is IR glass (Premium 2 Package). This feature leaves vehicle about 18 degrees cooler on entry which is huge in parking lots on 100 degree days.
Two worst features are iPod integration and navigation - both are incredibly poor and a total waste of money.