Hello,

I own a 1968 250SL and have been real active on the W113 forum, along with studying all the details of 230/250/280SLs. First and foremost, the 250SL is the rarest of the three but does not have any value increase as a result. In general, the pecking order of value (from high to low) is '70/'71 280SL; '68/'69 280SL; 250SL; 230SL. I opted for a 250SL because I found the later 280SLs were always higher in price and I had a budget cap. Quite honestly, I would be just as happy with any of the models...condition was the most important factor to me.

All 250SLs are improved over the 230SLs with the following:

Larger engine with 7 main bearings for smoother operation.
Four wheel disk brakes
Larger gas tank
Addition of oil cooler (via oil/coolant heat exchanger)
Various parts (not many) that are rare or obsolete on 230SL are more available on 250SL/280SL

Now here is the next valuable piece of information on 250SLs.....the 1967 model year 250SL shares the asthetic features of a 230SL, while the 1968 model year 250SL shares the asthetic features of a 280SL. It should be noted that the cut in for the 1968 model year was in July 1967. The main asthetic feature differences on the 1967 model year were the use of more chrome, different knobs and heater levers (more colorful), different exterior and rearview mirrors and lack of side markers on the body (only USA model had the side markers on the 1968 model).

The 1968 250SL added many safety features on the USA model. Regarding USA emissions, the 1968 model added the Fuel Shutoff Solenoid on the back of the injector pump...this system rarely works correctly and is usually disconnected...thus leaving the car free of emission controls (the later 280SL years added more and more emmision controls on the USA models, which can cause hard starting problems when hot). The injector pump on the 1968 model was improved by adding ball check valves versus the earlier cone values which can greatly improve starting the car under certain conditions.

I hope this helps!