Where should I start /w MPG on 87 260E
 

Filled up for the first time being able to check MPG. Got 21.5mpg with 50:50 driving.

I've heard this is a tad low and should be more around mid 20's for the 260E.

Where would you guys suggest starting to figure out the MPG?

Parts done so far:
New Bosch Ignition Wires
New Bosch non-resistor plugs
Checked rotor + cap and they visually look okay.
Idle air hoses
Throttle Plate set correctly.

I would start with a larger sampling. Try another 2-4 tanks and then see what you mileage is.

24 on the road, 17 in the city is about as good as it gets... i think you are right on target

we use mid grade in ours

And is your 260E running good?

How are you figuring your gas mileage?

What is your odometer error (if any)?

Have you checked your odometer against a measured mile? A GPS will work but not super accurate. It will give you an idea.

Are you running aftermarket wheels and tires?

You need to figure your errors (if any). Then correct the MPG at the pump accordingly. If you do not, then it is "all for not" and based on assumption.

Highest I've seen in my 300E is 21.5....its usually around 17.5-19. The M103's aren't a particularly efficient engine. The 260E probably won't be much more efficient, for what it lacks in displacement and power, it has to make up by working a little harder and using more fuel is my guess.

Full tank -- reset trip meter. Fill up and divide miles driven by gallons. Pretty accurate.
I'll follow the trip meter with a GPS...but they are pretty accurate.

This is with the stock 15" wheels.

You need to check your odometer over a measured 25 to 50 miles if you are using the GPS.

If it is that close, it probably will not matter. When you get into errors of 10% to 20% it starts to add up.

As an example... My current MB has a speedometer that reads right on the money according to GPS. BUT, over a measured mile there is a 20% error in the "odometer". IE: If I figure my mileage by these indicated figures pump/odometer = 21 MPG. If I correct if for my wrong odometer gear, my actual MPG is 26 and almost 27 MPG driving like a bat out of hell.

W124s for USA were not particularly good MPG cars.

It wasn't until the W210 and the 5-speed transmission and the new V6 that things got better.

W124: 3000+ rpm at highway speeds
W210: 2500+ rpm at highway speeds

After 1000 miles on the 260E, I have a total average of 20.9mpg. A low of 19.9 and a high of 22.1. (all trips about 50:50 city freeway)....I bet this thing only a long trip freeway only could get 25!

I'm gonna replace the rotor and engine temperature sensor as there is no history of the rotor being replaced and the engine temp sensor looks like it has been caked in oil and dirt for a long time and doesnt look too nice. We'll see if they make any difference. I figure if it helps even .5mpg it will pay itself back over a 6months.

This car goes about 115miles more per tank than my wagon! Thats how piss poor the mpg is on my wagon right now :(

Welcome to the wonderful world of Kjet.

It does also depend on your driving style though. If you are more of a leadfoot, then you are never going to get good fuel economy.

I do not race everywhere, and tend to drive very economically, like one of those hypermilers; except that i am usually late to wherever I am going. Does not make sense, I know. But most of my driving is on the freeway and I can get a very easy 25mpg with just about every tank in my 2.6. The E320 (1994) will be from 22- 25 mpg. My driving is probably 80% or more freeway. And I choose my routes that way deliberately.

My tires are one size larger, 205/65-15. My speedometer is dead accurate with this tire size on the 2.6. Havent checked on the 3.2.

Remember that the rear end ratio in the wagons and the 2.6 is the same, 3.27. So the different milage can be attributed to the larger engine and wider tires on the wagon.

I have owned a 2001 W210 E240 which in reality had a 2.6 V6, A 2004 CLK 240 which had the same engine and now have a 1989 Japanese spec W124 260e

I never have reset the mileage computer on either of the W210 E Class or W209 CLK.

Results E240 for 34,000 Kilometres = 10.2 litres per hundred K's which is around 24 mpg - combined city/country driving
Results CLK 240 for 38,000 kilometres = 9.8 litres per hundred kilometres which is around 25 mpg - combined city/country driving.

No computer in W124 260e but after about 15 tanks averaged about 13 kilometers per litre which is around 18mpg - combined city/country driving

MPG figures are for U.S. gallons not imperial gallons.

Interesting....the wagons have a 3.27 diff? Why? For potential towing use?

That could explain it right there why a 2.6 would get around the same or less mpg than the 3.0 M103....as it'd be running higher rpms and sucking more fuel. My 300E seems to run around 2900-3000 or so at 70mph.....

Amazing how much quieter a M103 is at 3000rpm than a 617. :D