I recently acquired a 1992 300TE 4matic wagon which is running well but RPMs on the highway seem high - about 3500 at 70 mph. I checked the fuel consumption on a recent interstate/secondary roads trip and got almost 24 mpg!. It definitely shifts through all 4 gears so it is either getting decent mileage even at these rpms or the tachometer is off - I did notice rpms were a bit over 3000 at 60 and bit under 4000 at 80. Is going to a lower diff ratio a big deal?
Quote:
Originally Posted by EuroCoupe
The two main things that cause this is the 4 speed tranny and the gear ratio on the differential. The factory gears on the 300E are 3.07, the wagons have 3.27 so they will rev even higher at cruising speeds. A customer with a 300E came into my father-in-law's shop 2 weeks ago saying he had a tranny problem because he was pushing nearly 4000 rpm on the freeway and thought 4th gear wasn't engaging. After looking at the car we figured out it was fitted with a 3.67 differential! Great for acceleration but deadly for gas mileage. Bottom line, these motors can run and were made to run ALL DAY at 3000-3500 rpm. No worries, just keep an eye on temp gauge to make sure all is well. Or go to a longer gear ratio like a 2.87.
Man, this topic is old!
Do you have the original diff on the car?
__________________ Shady
I drive too fast to worry about cholesterol. My CarDomain corner
2005 Mazda 6i ATX (She aims to please)
2005 Mazda 6i MTX (gives V8s a run for their money)
1987 Mercedes 300E (sold. They sure don't make'em like they used to)
1992 GMC Typhoon (sold. A lost cause!)
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This sounds just about right as these cars do not feature overdrive. Both my 124 and 126 have the M103 engine and these readings are within the norm i believe.
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1988 300TE, 251,000 miles
1989 300SE, 89,000 miles
2000 E320 4matic wagon, 115k miles
id say that 24mpg for a TE 4MATIC is great. all wheel and four wheel drive cars generally get worse fuel economy. and the touring and coupe models all had a numerically higher (better acceleration and load hauling, poorer fuel economy due to higher engine revs at any given speed.) rear end ratio.
in my 2.6 liter 124 i avgd 25 mpg on a long (1070 miles each way) trip at an avg of 75mph. bear in mind though, that i had to go through quite a few mountian passes in colorado and some awesome canyons in southern utah. on the really steep climbs i dropped it into 3rd and ran at near 6000rpm to maintain my speed. when i got home and ran the numbers i was initially disappointed that it was that "low" but to avg 75 meant there was some 100mph plus driving, and all the mountain passes.
then a quick peek at fueleconomy.gov showed the EPA rating to be 23 and i beat that. not to shabby for a 17 year old car.
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