Have noticed on my E350 Coupe that the heated seats take a rather long time to get up to some heat comfort, the BMW that I have just come from the heated seats were very quick to heat up . 
Merc Owner 2B
MB Enthusiast
I had the same car and they heated very quicker and and got quite hot.
Do both of your front seats act the same? sounds like a poor connection or seat pad.
Check all the electrical plugs under the seat for secure connection.
Do both of your front seats act the same? sounds like a poor connection or seat pad.
Check all the electrical plugs under the seat for secure connection.
