I have a 2006 CLS 500 with 122,700 miles on it. Lately, it has been slow to start the first time I try after sitting overnight. It cranks strong but takes from 5 to 10 seconds to start. After the 1st time, it starts immediately. Its not giving me any codes and the check engine light is NOT on. (Actually, I am getting an ABS code with my scan tool but I don't think that is related to this issue). I just had the auxiliary battery replaced, also had the front passenger air strut replaced. I thought it might be the MAF sensor since I have seen cars act this way with MAF sensor issue. I cleaned it but no improvement. I also changed the air filter. I thought it might be the crank sensor but cars with that issue will usually stop at a light or something or refuse to start until the car cools off. Neither of those has happened, except cooling off for an extended period such as overnight. So, I thought I would ask the forum before I start throwing parts at a problem.