Fuel consumption

[AshleyME]

Hi,

I have a 2013 W212 E220 CDI, I find that for some reason I seem to be going through a decent amount of diesel, that gauge says I’m getting 45.5 mpg daily but I seem to go through 3/4 of a tank a week for around 200 miles despite 15 miles of this being motorway driving with cruise on at 70-80 mph.

anyone know if there is an issue or any ways to improve this? Or if this is just how they are?

I was thinking of remapping the engine to give it more power to use less revs and carry the weight easier.

let me know what people’s thoughts are?

Thanks
Ash

 

[artyman]

In my C class it can read anything from 3-5 mpg optimistically, not a reliable indicator at all, cruising at 65 will improve consumption yet only add a seconds to a 15 mile motorway stretch, a light right foot, anticipate braking and coast more.

 

[grober]

Despite the plethora of fuel consumption digital readouts the most accurate measure of fuel consumption is till volumetric- volume of fuel dispensed from pump to fill tank versus miles travelled -On a more general note fuel tanks sizes in many models are decreasing for reasons of weight reduction

 

[W1ghty]

Hi,

I have a 2013 W212 E220 CDI, I find that for some reason I seem to be going through a decent amount of diesel, that gauge says I’m getting 45.5 mpg daily but I seem to go through 3/4 of a tank a week for around 200 miles despite 15 miles of this being motorway driving with cruise on at 70-80 mph.

anyone know if there is an issue or any ways to improve this? Or if this is just how they are?

I was thinking of remapping the engine to give it more power to use less revs and carry the weight easier.

let me know what people’s thoughts are?

Thanks
Ash

The only way I check to see if my E320cdi is working efficiently is to reset the mpg thingy when the car is warm and I’m doing a steady speed on the motorway on cruise control . If the figure is similar to the last time then all is ok .
Low numbers below expectations could just be to do with how you drive and what sort of town/motorway driving you are doing .
Diesels also can take a while to get to operating temperature and it’s only at this point they become efficient .

 

[AW8]

Allegedly stated official mpg figures may not be anywhere near attainable.

Allegedly some members may struggle to get close to brochure figures.

Allegedly real use emissions & mpg varying somewhat from real world figures.

Allegedly there can be variance between displayed mpg & real mpg but this should not be excessive. I am relatively new to Mercedes but know that it can be possible on some cars to change the parameters in hidden engineer modes so that the consumption displayed better reflects fuel actually used.

As for whether your specific car has a fault which is negatively impacting consumption &/or display accuracy I have no idea. Your car would need to be checked with the appropriate diagnostic kit &/or looked at by a main dealer or specialist with the right skills & kit.

If the car has prior had a remap then this may be another factor in the equation

Do be mindful that if you go down the diagnostic & possible repair route you will be likely be also steered towards ensuring the car wants for nothing that could have negative impact to mpg...this means fluids, and relevant filters.

Assuming your, (standard not long range), tank holds the specified 59 litres, (some have reported filling more), then 3/4 of a tank would be 44.25 litres & 20.55 mpg which is half the figure you say computer tells you of 45mpg ! To add another factor ...I believe fuel gauge needles are usually NOT accurate representations of fuel in a tank.

You probably know this but bear in mind that professional diagnostic work comes at a cost....albeit you may get some costs back if matters can be sorted. No point wasting time & money getting this looked at unless its with someone competent & with decent kit.

If it helps I would expect digital display to show 33-35mpg local runs on & cold engine. On the motorway at 60mph indicated I would expect to see digital consumption displaying 50mpg or more. I have a 2011 E220cdi 7g+ auto ....all fluids & filters recently done. I do a 240 mile every few weeks & around £30-£35 of premium diesel gets me there and back, (according to the needle). Don't try to do more maths based on my figures ....this is just to give rough ballpark comparison figures.

Allegedly fuelly data website & reports of others suggest the official figures can be around 20% optimistic...........but do bear in mind that diesels do better when warm & on longer steady runs.

Sorry I cannot be more helpful, (or precise with the numbers)

Good Luck

 

[markjay]

The reading of 'quarter tank' etc on the fuel gauge is extremely inaccurate.

You need to work-out the fuel consumption by checking the amount of fuel brim-to-brim, preferably refueling at the same pump at the same time of day, then dividing the miles travelled by the amount of fuel (after converting litres to gallon). The miles reading on the odometer will also be inaccurate sadly but there's no way around it.

 

[Jockster]

Hi,

I have a 2013 W212 E220 CDI, I find that for some reason I seem to be going through a decent amount of diesel, that gauge says I’m getting 45.5 mpg daily but I seem to go through 3/4 of a tank a week for around 200 miles despite 15 miles of this being motorway driving with cruise on at 70-80 mph.

anyone know if there is an issue or any ways to improve this? Or if this is just how they are?

I was thinking of remapping the engine to give it more power to use less revs and carry the weight easier.

let me know what people’s thoughts are?

Thanks
Ash

Hello Ash, if you are getting through 3/4 of a tank over 200 miles something is wrong, that should be closer to 1/4 of a tank, if you haven't any warning lights I would take it to an Indie to get checked out, whatever it costs you will more than likely re-coup it from the fuel savings when fixed.

 

[W1ghty]

When you add your “3/4 “ of a tank , write down the gallons and then you know for your 200 miles what the mpg was ...simples

 

[Deleted member 149005]

200 miles on 3/4 of a tank does not equate to 45mpg...