Since the time I bought my '73 280 SEL I have gotten about 11 MPG on average. This was mostly in town driving, with occassional hops on the interstate. Best I ever saw was 12.5 MPG, and that was while really babying the throttle for the whole tank.

Last weekend I took the family on a run across the mountain to meet, visit and have dinner with another forum member, JCE AKA John Elliott and his wife. I fueled up on the way out of town, and ran hard through the mountains, enjoying the curves and the power of the 4.5 as I accelerated up the grades and staying cool with the A/C blasting, basically said "to heck with the mileage", and enjoyed the ride. That trip, plus almost a week of in town driving, I got 15.04 MPG.

I am at a loss as to why I had such a big jump in mileage. It wasn't city driving by any means, but I ran hard and really expected to get about 10 MPG. Any ideas as to why the big boost in mileage?

To Deezel: Also interested to hear what kind of mileage Suzanne gets on each leg of the trip home.

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Mike Tangas
73 280 SEL 4.5

Perhaps your "run across the mountain" put the engine under sufficient load to blow excess carbon out of the engine. Or should I say it burns it out? I've been taking my 1984 300SD turbodiesel out on some longer drives, and on the way back I cross South Mountain while holding the transmission in "L" keeping right at the posted 40 mph speed. This puts my engine speed close to redline. Not a good area to speed since the speed limit drops to 30 mph thanks to a well-hidden sign near the top, and all the way down. By the top of the hill the temp climbs about five degrees, as well as leaving a nice cloud of smoke.

I've been enjoying improved driveability as well as a 1-2 mpg increase in mpg, and this is on the tanks where I crest a mountain in second at high rpm's. I know we have different engines but this was just a thought.

Another is the amount of time spent in the lower gears in city driving. If you're driving hard on highways, you'll be in top gear most of the time. My car averages about 19.7 mpg in city driving, but on the highway I get 25 or so.

[This message has been edited by Robert W. Roe (edited 09-07-2000).]

Sounds like an "Italian Tune-up" to me.
AK
260E
FIAT 124 Spider

I have made runs previously to the big city, 190 miles round trip, with no increase in mileage. Those were all highway miles too. The main difference between the last interstate hop and the mountain trip was the change in plugs. I got rid of the plats and put in copper cores. Could be the combination of plug change and blowing out the crud was the key. What ever the case, I'm not complaining. We'll see what the next tank does.

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Mike Tangas
73 280 SEL 4.5

You are one VERY VERY VERY lucky duck...from the Vancouver Province, gas prices are sitting at around 80 cents Cdn a litre for REGULAR...yeah, you heard me...SUPREME is sitting at a comfortable 90 cents Cdn a litre...(that is what most of us M-B users use right???)

For you Americans, the Province did a comparison and wrote that in Blaine, Wash., the price for regular at the USA MiniMart: $1.699 US a U.S. gal., or 66 cents Cdn a litre, unchanged.

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1995 Mercedes-Benz E420 (W124 - Black Pearl/Black)