A friend of mine who runs a small workshop has just bought a Mercedes Diagnostic tool. I have a 2004 model clk55 AMG, standard apart from quad exhaust, fitted after secondary cats, pretty much straight through pipes after. When driving slowly in Auto, the gearbox changes so that at times I am only going 20/30mph but auto has put the car into 5th gear. There is no need for it to be in such a high gear at such a slow speed. My question is, what can my friend do via his Diagnostic tool to improve things and how to do it? What else could be done via diagnostic tool to possibly make the car run better? Thanks in advance.