That is not a reliable method of checking mileage.

Tom W

One time might be questionable, but he did it 'several' times which makes the result a little more plausible.

I have no intentions of proving anything. You can take what I learned and use it or be hard headed and say I don't know what I am talking about or how to add and devide. I am 65 years old and my whole life I have loved to try things and learn from it. A lot of what I have learned is of no use but I still learned something from it. I have a friend that has a 87 300SDL and he can get over 28 MPG on a trip so don't tell me a 126 can't get 28 MPG at 70+MPH. I have made my point, some people just can't take the word of others and learn from it. By the way, with my 500 adjusted and set up as stock it will only get 12 to 14 in town and 20 on a trip. It runs great, does any thing I ask of it. I keep it basicly stock and love it BUT it is possible to get 28MPG. Will you believe i can get 32 mpg in my 300D withouy even trying?

Leaning it enough to affect mileage and advancing cams? Just guessing really.

A gas engine needs from 1/13 to 1/14 parts fuel to air to run. Richer or leaner will result in real problems. Turning 5 liters of air for every other rotation of the motor will result in a very predictable amount of fuel being used. Since I know what a 500 motor will do from personal experience you telling me that you got 40% better fuel economy causes great scepticism. I never assume anybody deliberately tells untruths so I must assume that a mistake was made somewhere.

I don't believe that you have somehow discovered a magical formula for excellent fuel economy in a 500sel.

Tom W

What started the advancing cams idea was the new engines with VCT (variable cam timing). The exhaust cams are advanced much like the ign timing is advanced at higher RPM. It is not practical to just advance the cams and leave them that way because it greatly effects other aspects of the engine operation, mostly idle and low rpm. Plus, I had to advance both intake and exhaust since I only have one cam on each side. I put the cams back at 0* after the trip for this reason. Tires at maximum pressure caused very rough ride and wear problems. I put them back to the recommend pressure shown in the gas cap door. My background is in computers and I have a reasonably good understanding of how the on board computers work and can tell you they run the engines lean under certain conditions, such as high vacuum. I didn't run the engine in an extreme lean condition but adjusted it using an O2 sensor to .3V at 2500 RPM or so under high vacuum conditions. This is a little lower than the .45V which is considered ideal. The euro CIS on this car has no provisions for mixture control so some aspects of performance were compromised by the lean mixture, but not the constant road speed. Remember, all of this was an experiment to see how much mileage I could get. Did it turn out to be a magic means to get more MPG. No. I just used some of the advances designed by the manufacturers. Mine were crude but cheap. The MSD system I already had was used to fire the plugs set at .60 in under these lean conditions. The plugs are set to .40 in now and the engine never misses a lick. Try that with a stock setup. Drafting trucks is not recommended but it does help with mileage. And also remember, most of this 2000 miles or so was on flat ground, no stopping except for fuel and food and nature calls. Did I learn something. Yes, it can be done. Would it be practical, no. Will I do it again, no. The only thing I can say now is if you don't believe it, try it your self and see.