poor gas mileage/1973 450sl
 

I have driven the car all week and have managed to get only 100 miles out of a tank of gas. I popped the hood and found the air cleaner hose disconnected from the crankcase. I reconnected it. How much did this contribute to my poor gas mileage? thanks

Very little I imagine.

That D-jet system needs a bunch of extra timing and a fuel/timing combination that gets 17in of vacuum at 800 rpms and you will get decent mileage.

I'd start with about an extra 7 degrees of timing and if an exhaust gas analyser isn't available go lean untill it runs bad and then go rich until you first reach highest manifold vacuum, hopefully 17in..