How many miles per gallon should I get on a '74 240d? I have heard from different people ranges from 35 to 50. However, I'm getting a solid 20, and that just doesn't seem right...especially since it's mostly highway driving. What should it be, and why is mine so bad?

 

Driving style is one of the bigest factors of MPG, and people tend to bend the truth a little. My 87 300D gets better MPG on country road were 45-55 mph than interstate driving at 70. Most diesels in my experience get the best MPG if kept at or below 2000 rpm

 

But I think I also need to get the valves adjusted (was supposed to happen this last weekend, but didn't), and I might need to take a look at the injectors too. It also doesn't help with the RPM's that they replaced the tires, and put 60's back on it, when factory specs are 75's...also throws off the speedometer.