Before I talk mileage, I would like to say that I have read some of my posts, and they have been a little strong worded. Not my intent, and not really me. I hope I haven't raised too many eyebrows.

So, far, I haven't seen a lot of confessions about FUEL MILEAGE (on any website), but I bought my 240D with the hopes of good mileage. Earlier I said, the quest was to hit 40MPG, and it is not in me to say that I may not make it. I don't have enough information, yet, to rule this out.

I have seen a number of postings on a number of websites, where people wanted to know what kind of mileage is possible on these cars. I have two responses, as I had a new 1980 300D which was pushing 38 MPG at 55 MPH, strictly highway driving (this was 1981).

So, let's get into response number 2. And now I have this car, and I would report this. I just drove 660 miles on 23.95 gallons. I slowly filled the tank, so that I could get it to 3" from the top of the neck on the tank. Of those miles, 380 (57.5%) were driven around town. In many cases, it meant driving a mile to the grocery, and then returning. I did four road trips for which I kept track of the mileage. 80 miles of the last run (moving my kid), I had the car loaded with clothes, suitcases, and a single matress up on the top of the car (last time I do that). Also, for the young people reading this, never put a matress on the roof of a MB, unless you open the sunroof. I learned this lesson in the 1980s. So, with 57% local driving, and 43% highway, the car delivered 27.6 MPG. Now, I don't know how to figure this in, but I was trouble- shooting the vacuum system, and the car idled about a half hour doing this (in other words, there were no miles driven when counting MPG), and it did detract from the mileage somewhat. At 27.5 - 28 MPG combined, my 300D did not do that. I also took the car to 85+ MPH several times to blow it out, and see if it held together. I have not been bending over-board for mileage, but this is where I am. I would also like to say that when I bought the car, mapquest.com said my trip home was 1400 miles (MIAMI / CHICAGO, that is also what my odometer said it was.

At this point there are many things to consider. I still haven't done a compression check, but I know the engine is "tight." There is a guy named Russell, online, who shows how to do a valve adjustment, and he suggests using a wrench and turning the nut on the steering pump (to rotate the engine). Well, I tried that to prepare for the valve adjustment. I couldn't come anywhere near turning this engine, not even with one hand on the wrench and the other tugging on the belt. I figure the compression must, overall, be quite good. I need to adjust the valves, as I know it has been a long time.

That leaves injectors. I called Bosch, and they tell me that they rebuild the injectors so they OPEN at 100 bar, or 1450 PSI. This makes no sense to me, as Mercedes says the minimum they want is 1450. Why build an injector to minimum spec? I see these Monark injectors, and people say they are better than the Bosch injector because Bosch is essentially rebuilding injectors using a 30+ year old nozzle design. 1500 PSI might make sense with a "tired" engine. I don't know.

I WANT 40 MPG for highway driving. NO, I WANT TO BEAT THAT. I am not changing my tune, and more is better. Anyone who read paragraph two above, and thought I had my doubts, just plain does not know me. Any help, any idea, will be greatly appreciated. I will pass on my results to everyone who reads this thread. It may take me another year or more to get the most out of this car, but I am not giving up, I am moving forward. Anyone that wants the best MPG should continue to watch this thread. Why?

There are unanswered questions here. Monark nozzles must be good, but do they give the best MPG? I don't know. Are there other choices for nozzles? I don't know. I am not feeling good about Bosch's solution, or the lack, thereof. Is there a way to improve any of these nozzles? I don't know. But, I am going to try to find these answers. I have questions like this. If you increase the PSI that an injector POPS, does that, in effect, delay timing? I don't know. Think about it. If one injector POPS at 1450, and one is set to POP at 1700, this would seem to delay detonation. Seems like common sense to me. Can an injector be set to deliver less fuel into the cylinder, thereby increasing MPG? I don't know. But ask yourself this. If the injector is set to POP at 1700 PSI, and not 1450, would it not need less fuel to detonate at the higher pressure? I don't know, but I would like to find the answer to this question, as well as others stated. We now have 30 year old engines. Some have compression of 200 PSI, and some are 275, 300, and maybe 350+. I think most would like to know how to adjust our engines given the amount of life (compression) left in them. We like these cars. It doesn't cost more to know these answers. I am sure Mercedes could help. We just need the right person there who can jump on my Don Quixote bandwagon to the Road of Enlightenment (Sean Connery, "father to Indiana Jones").

So, I add this. It is another PMA. It was written by my good friend, anonymous. It matters not who wrote it, because when you are done reading it, you will know everyone can profit by it. So, one more PMA......








Don Quixote's bandwagon is a big one, and there is room for all. Please help me find the answers. Please help all of us find the answers. Corny, but true, BUT also worth the effort.