Sorry but this is not true, and there is no need to change noting if you get "tuned", and yes good quality tuning gets better MPG as well, i had C320 was getting 15-17 city driving easy/traffic to 19-20, highway was improved as wellI'm thinking about adding a chip to my car too. Can you tell me how ur gas mileage is and the octane you put? I've heard u need a higher octane that US doesn't supply.
Europe ave better/higher octane fuels, but worldwide mb cars most of the time wen drive hard you can smell sulfuric acid on the tailpipe this is actually for rich running condition, and retarded timing advance so is able to run ok even if is lower octane fuels, but the rich running condition is bad for short driving trips really badThe only reason it seems like europe has better gas than the US is becuase they use a different scale of measurement. They use the RON scale while the US uses the MON and RON values and averages them.
Chips do a lot more for the NA mercedes than one would think since mercedes runs their motors quite lean(about 14 AFR when WOT). So when the fuel ratios are changed to more performance minded fuel ratios, the car gains a lot of torque and usable horsepower.