I have a CLK that has me stumped. I am getting 18-19 MPG combined in town and HWY. It has 73K miles and is in very good condition. Recently changed plugs, OEM wires, fuel filter, and still the same. My local indie shop says no to a fuel injection service because it can cause more problems than it solves. Another indie says do it and you may see improvement. I had a 99 CLK 320 that got high 20s MPG. Is the new generation V6 that much worse for fuel economy? Thanks for any opinions.

 

My 2005 CLK320 averages about 25mpg at 75 mph on the hwy. I only use super unleaded with tires properly inflated.
I have 49K miles on mine

 

My 2005 CLK 320 gets 22 mpg. Mix Hwy and city driving. Premium gas and proper tire inflation. So it seems like the 20-25 seems to be the range.