Owned this 07 GL320 CDI for 15 months. Overall fuel efficiency has been 22.7 mpg through 20500 miles. On the highway, we've gotten up to 28 mpg, and always 20+ around town. Very comfortable on long trips or short commutes. Handled heavy winter snowfall in Spokane and North Idaho with ease. Couple of items to be aware of when purchasing. Uses synthetic Mobil 1, so oil changes are every 10- 12k. Oil light comes on occassionally. Dealer states it's a computer glitch that hasn't yet been corrected. OE tires (we have Continental 4x4 Contact 18") are worn out and need to be replaced.
Great ride. Great handling. Goes a long, long way between fill-ups!
Tires wear out at 15-20k, and cost about $1k to replace! Fix the oil monitor - gives false 'add oil' warnings.