Thinking of switching to a W212 Saloon

[Blooregardo]

Hey there fellow Mercedes enthusiasts. I'm currently looking at various listings of 2010/2011 grey import W212 models to replace my 3 year old 2012 BMW F10 520i. Grey import cars are extremely popular where I live. But I'm a little bit skeptical of the mileage's that are advertised on these cars, specifically the Japanese imported ones. Most of them have from 10,000 - 15,000 KM which I find to be a little bit too optimistic for 5/4 year old cars. So, what should I inspect for on a W212 to indicate that it is low or high mileage and is there a way I can check the actual mileage if indeed the car has been clocked ?

Thanks in advance !