1987 300D vs 300SDL performance
 

My 1987 300D was no-op since I bought it 4 months ago. I fixed some minor issues, registered and drove it last week and it is a completely different car than the 300SDL. They have the same OM603 engine but the 300D performs like a gas car, quick off the mark and very peppy. The SDL is like a snug from stop but they seem to perform the same on the open road.

Anyone with both cars and can relate to my observations? SDL is too heavy or something wrong with it? Any comments is welcome.

The ALDA has been adjusted on the 300D, it only affects off the line power, once you are on the open road it would feel the same adjusted or not.

Maybe but
 

The 126 is a much heavier car with a longer wheelbase. In my limited experience behind the wheel of SDLs, they are slower and less agile than 124s. I have never driven a 126 on a freeway so I also have never made a long trip in one. The turning radius of a 124 is one of the best features of the car.

Different cars, but all things being equal, the SDL weighs more and has a longer wheelbase. Both of these characteristics will cause a noticeable difference in off-line performance and handling favoring the w124 over the w126

Take the ALDA off the SDL and then compare. An SDL without an ALDA is not slow.

I like my cars stock. I just want an opinion on the comparison.

Then adjust or shim the ALDA....that way it's still stock. To get a fair comparison, you need to optimize the SDL.