stupid question from a new owner...

I bought a 1993 300E and I don't know if it has the 2.8 or 3.2. The owner's manual is generic. Is there a sticker on it?

....but was wondering the same about my 1988 300E. Owner's manual doesn't specify the engine size in it either.

It's not always true but for both of those cars the 6th and 7th digits of the VIN designates engine size in liters - e.g. 28, 30, or 32. A 1988 300E would always be a 3.0 liter as a 2.6 liter was called a 260E. A 93 "300E" would be a 3.2 as a 2.8 was actually called a "300E 2.8", at least on the title. Of course some cars have had the "2.8" trunklid emblem removed.

Just type in your VIN .
It will give you the full pedigree

http://old.mbclub.ru/mb/vin/?lng=eng