apg231

So I thought the E Class had a 21.1 gallon fuel tank? Today I let mine get down to where the red reserve fuel light came on in the MFD (prior to this it said I had a 26 mile range) so I was surprised when I filled it and it only took 18.5 gallons. Is the reserve really 2 gallons? I don't want to test it to find out.

PLINYELDER

Tank is 21 gallons.

apg231

Yes, I know that. My question is why when my tank was almost empty did it only take 18.5 gallons?

thefisch

Most I have ever filled up according to my records is 20.116 gallons. I routinely have fill ups in the 18-19 gallon range when the needle is just below that last notch before 0. Only about half a dozen between 20-20.1 over the last 3 years - on those the needle is right at 0. I have a short commute with several gas options so I normally wait until it is a convenient time/location unless I am planning ahead based on my schedule. I always stop filling when the pump clicks off too - made that mistake once already. MB is more sensitive to topping off, not like my past Honda/Toyota cars that could get an extra 0.5-1 gallons in there.

I think when you get below 25 or maybe 20 miles to empty, the readout goes away and you get an icon of the car at a gas pump - like you don't know what that looks like.

Since I average 18mpg during normal driving, 26 miles to empty is a 18-19 gallon fill up for me in my experience.

tresean1

I tried the experiment last night...got that little image on the car at a gas pump.
Went to the gas station, and put about 10 gallons or so in...needle went to halfway mark.

So I guess a full tank would necessitate +/-21 gallons of fuel (of course I was averaging 31-34 mpg).

kajtek1

The reserve is always pretty conservative on all cars.
I hate pulling for fuel with 1/3 of the tank, so often I test the reserve with spare can in the trunk.
On gasoline E320 I had initially about 50 miles range when reserve light come on.
The range display was acting crazy as after 30 miles it was showing 15, another 5 miles cut the range by 10.
Anyway, I drove till 0 range and then another 10 miles, still pulling to station with no hesitation.
Diesels don't like to be run dry, but then when lights come on, it usually shows 70 miles range.

apg231

Thanks for the replies, so it seems like the reserve is pretty good size. I did let my car run down until the symbol of the "car at the fuel pump" came on, but like I said, prior to that it said I only had 26 mile range. I am certain the car could go farther on 2 gallons than 26 miles. Maybe I will stick a 2 gallon gas can in my trunk and really test it out.

raja777m

Please do a video on it too; if you're planning to test it out.
Thanks.

mikemargolis

I've had four tanks that took more than 20 gallons:

21.208
20.543
20.007
20.004

Being a 3 liter diesel, I've also had four tanks that went greater than 700 miles

730.00
725.00
715.00
706.00

kajtek1

Learn how the tank works first.
I know for example that W211 and W163 do have 2-chambers tank, when Venturi pump powered by returning fuel sucks the fuel from "dead chamber" to "pump chamber"
When you don't have returning fuel to transfer the fuel from dead chamber, it takes about 5 gallons to overfill dead chamber and get fuel to the pump.
Even smart forum members got nasty comments when they call MB roadside assistance after putting 2 gallons of fuel in stopped car.

VegasE

Yeah the reserve is about 2 gallons, as it is on most cars. Folks should verify this after buying a car by filling up shortly after the light comes on. Do not trust the "miles to empty" reading at this point because it will change wildly based on driving conditions and the gas moving inside the tank. It is generally a bad idea to drive far with the light on because you will suck any residue in the tank into the fuel filter and shorten its life.