21mpg on W208 - whats wrong?

[allias]

Could someone tell whats wrong with my car as I get quite high fuel consumption (when I compare to other CLK owners). My CLK is '99 and its 230Kompresor. I dont know if it make any diffrence but I got 18" "Look a like AMG" with 245/40-18 tires.

It doesnt matter how I drive I always get 21-22mpg (sometimes lower). When I drive in a city I do get "heavy foot" once a while but even if I will drive like a nun I get similar mpg. When recantly I done motorway miles I got 24 mpg.

I think its really pricy for me to run a full tank. 300 miles for over £60.

Whats been done within last 3000 miles since I got it:
1. oil change
2. full tranny service
3. fuel filter changed
4. regulary checking tire pressure for correct level
5. done alignemnt (had some wrong angles making extra resistance on wheels)
----- cars runs fine and very strong - no engine faults - its been scanned - no problems noticed ---------

 

[Stratman]

Your best bet is to take it to a garage with STAR. That will show any fault codes stored and whether or not there is a real problem. There are so many things you can throw money at and not cure anything, a STAR session is money well spent.

 

[wemorgan]

Short of any mechanical and electrical faults it sounds as if the fuel efficiency is simple a result of your wide tyres and driving conditions.

For reference my CLK320 with 16" wheels would give ~30mpg on motorways doing 60-70mph.

 

[allias]

Your best bet is to take it to a garage with STAR. That will show any fault codes stored and whether or not there is a real problem. There are so many things you can throw money at and not cure anything, a STAR session is money well spent.

Stratman - already done this. Had some broblems with brake switch and something on gearbox but that was all sorted. No faults since. Clear and no faults. Been done twice. Before and after all fix done to listed problems. That was 1500-2000 miles ago. Still the same problem with mpg.

wemorgan - will it change if I would drive it on narrow and smaller wheels/tires? Im not so sure about this as I would have lost 50% against 16/17". Dunno...

 

[wemorgan]

wemorgan - will it change if I would drive it on narrow and smaller wheels/tires? Im not so sure about this as I would have lost 50% against 16/17". Dunno...

It's hard to say, but somehow I would imagine a 10% improvement with 16" wheels, but still not great mpg.

Smooth and relatively slow driving as been my recipe to good efficiency. But I appreciate that's not palatable to most people.

 

[Vlad]

Sounds like your car has some issues....when I had my CLK230K I used to easily get 38mpg on motorway runs and @ 28mpg at other times.

 

[Tan]

I think the fuel consumption on my E500 is low and it was mentioned to me that it could be a faulty MAS sensor, not sure if this could be an issue with yours.

 

[Sonny Burnett]

i have gotten 35+ on motorway in my 230k

 

[jeremytaylor]

Shouldn't that be on the freeway?

 

[allias]

Wow... so wtf is wrong with mine? I dont even know where to start.

 

[Bobby Dazzler]

MAS/MAF sensor is a possible cukprit - but there are many - and it would typically also cause other strange behaviour, so a possible, but not a probable.

It could be normal, depends on what sort of driving you do - to try and eliminate it being normal for your style...

If it's an auto do you use kick down, or hang on the gears?

Have you checked your tyre pressures?

How many passengers do you typically carry?

Do you have to accelerate briskly from standstill to a high speed?

How far is your typical journey?

What's the indicated engine temperature on the gauge?

 

[allias]

If it's an auto do you use kick down, or hang on the gears?
-- There is enough power on normal band so I hardly ever use it

Have you checked your tyre pressures?
-- I do it twice a week as I had problems before and Im very cautious

How many passengers do you typically carry?
-- Its usually just me.

Do you have to accelerate briskly from standstill to a high speed?
-- It depend but even if I try to be slowest driver on road or if I got motorway miles its still very similar.

How far is your typical journey?
-- Most of full tanks I use for work trips - 5-6 miles one way.

What's the indicated engine temperature on the gauge?
-- Always normal - 80-90deg

 

[The Pan Man]

Surely if it was the MAF the OP Would have noticed a deterioration in the performance. The stated MPG is way too low unless its heavy right foot all the time and the OP says not.

 

[jasonyw]

Don't do anything. It normal. Didn't you know the gas consumption before you buy it? That why the tax rate is £400 next April.

You want a super car, this is what you get.

Kompressor(super charged) is even higher gas consumption, idling in heavy traffic in town.

Next time go or 1.8l, even though it such a tiny engine, gas consumption is still high on heavy foot on the accelerator.

If you are concerned about gas consumption go for a BMW.

 

[vincenz]

Don't do anything. It normal. Didn't you know the gas consumption before you buy it? That why the tax rate is £400 next April.

You want a super car, this is what you get.

Kompressor(super charged) is even higher gas consumption, idling in heavy traffic in town.

Next time go or 1.8l, even though it such a tiny engine, gas consumption is still high on heavy foot on the accelerator.

If you are concerned about gas consumption go for a BMW.

Jason: The 230k is a 1.8 and not a super car and BMW's are no better.

OP: can you reset the trip counter and see what it delivers at 50mph on the motorway?

 

[d w124]

If you are concerned about gas consumption go for a BMW.

Don`t know about now days,but a pre 2000 BMW is better?!!!!

 

[BTB 500]

Could someone tell whats wrong with my car as I get quite high fuel consumption (when I compare to other CLK owners). My CLK is '99 and its 230Kompresor. I dont know if it make any diffrence but I got 18" "Look a like AMG" with 245/40-18 tires.

It doesnt matter how I drive I always get 21-22mpg (sometimes lower). When I drive in a city I do get "heavy foot" once a while but even if I will drive like a nun I get similar mpg. When recantly I done motorway miles I got 24 mpg.

Are you getting those mpg figures from the cluster display?

Reason I ask is that I think your tyre setup is wrong - should be 225/40 on 18s:

Alloy Wheels Direct Ltd | Fitting Chart Index

This will make the mpg (and speedometer ...) under-read slightly, as the car is actually going further on each wheel rotation than the computer thinks.

I reckon by only about 3%, but this is likely to be part of your problem. If you check the mpg the old-fashioned way by logging fuel put in and miles covered it should come out a little bit better.

 

[allias]

I dont have on-board computer. The way I check it is by filling full and dividing by amount of miles.

As far as my knowledge about fuel consuption: I knew about it but when I read post on this forum and see where ppl are with bigger or the same engines thats why Im concerned.

Overall its not something Im not prepered for its but it would be great if I could save 40-50% on mpg and reach somewhere about 30+.

As far as tyre size... I thought it could be a problem, but will it be sooooo high?!?

 

[corned]

How far is your typical journey?
-- Most of full tanks I use for work trips - 5-6 miles one way.

Personally I think this is where your problem is more likely to lie.

Short journeys are not conducive to good mpg - simple as that. If you were doing journeys of 40 miles plus, then you'd have cause to worry.

Added to that, the tyres are possibly exacerbating the issue.

 

[Howard]

Agree with corned .

5 or 6 miles is nowhere near enough to warm the engine up.

Most of my journeys are to work and are only 2 or 3 miles , and i struggle to get more than 15 mpg. Ok , mines a V8 but horses for courses.

Do a motorway round trip of say 60 miles , driving sensibly , accelerate up to speed limit and sit there . You should be getting 30 mpg plus.