In my quest to buy an E55, I tested 2 other E55's and settled on an '05 - had the right color combo/options - also, it 'felt' faster - is there any way for me to verify if the ECU had been flashed?

 

that's a good questions...when i bought my C32 it had ASP pullies and other upgrades I had no clue it was upgraded since i had never driven any other C32, it moved very fast, I found out when I took it to the dealer because the water pump broke so they replaced it with the original equipment, what a difference felt so slow... The mechanic said it had aftermarket pullies so it almost voided the remaining months in my car (warranty). Good for me my service advisor intervened and covered some of the faults. I was able to keep the warranty. I guess you could always take it for a Diagnostic test to the mercedes dealer or any other performance shop.., they should be able to help in that aspect. Hope this helps.