Excessive fuel consumption

Flyer · Post by **Flyer** » Mon Nov 27, 2023 12:24 pm

Hello all, I’m a new owner of a 2003 plate 2.5L E85. When I got the car it had massive vibration on the steering and a check engine light. I got a relatively good deal so I took it anyway. I have done some extensive preventive maintenance on the car, but for the sake of this post I will list down what’s more relatable to this post.
- airflow sensor
- all 4 o2 sensors (as it turns out it was fine but oh well)
- spark plugs
- and a few of the hoses after the air filter

The fuel consumption of the car is high, about 280 miles per full tank of unspirited driving. No more fault messages and nothing appears when it’s plugged into a computer. Any ideas what I can look for? Thanks!

Flyer · Post by **Flyer** » Mon Nov 27, 2023 12:26 pm

As for the vibration of the steering wheel, I changed the front arms and it died down about 97%. I still feel some tramlining but looks like I have to change the steering rack and tie rods.

MikeyH · Post by **MikeyH** » Mon Nov 27, 2023 12:53 pm

Hi, welcome to the forum.

Mine has tramlining and darts about a lot. It seems to be normal on these cars. Have you still got the run flat tyres, these don't help at all. Also 4 wheel alignment helped to ease mine a little.

Flyer · Post by **Flyer** » Mon Nov 27, 2023 1:01 pm

Yeah I ditched the run flats and got Michelin ps5 all around, with a cheap TPMS that should tell me when I’m in trouble. I haven’t had a look at the rear arm though, but I know for a fact the steering rack probably needs to be changed, and the tie rods.

MikeyH · Post by **MikeyH** » Mon Nov 27, 2023 1:22 pm

Flyer wrote: ↑Mon Nov 27, 2023 1:01 pm Yeah I ditched the run flats and got Michelin ps5 all around, with a cheap TPMS that should tell me when I’m in trouble. I haven’t had a look at the rear arm though, but I know for a fact the steering rack probably needs to be changed, and the tie rods.

Okay

Five-O · Post by **Five-O** » Mon Nov 27, 2023 1:59 pm

Is that high consumption? I get about that too. I only do quite short journeys though.

buzyg · Post by **buzyg** » Mon Nov 27, 2023 2:02 pm

Welcome to the forum.

What is that in MPG?

z.sb_E85 · Post by **z.sb_E85** » Mon Nov 27, 2023 3:09 pm

Welcome! I’ll get anywhere from 270-300 or so miles on a full tank so it seems like you should be good? Unless we both have an issue!

Flyer · Post by **Flyer** » Mon Nov 27, 2023 3:55 pm

I had a friend with the same engine 5 series and he was getting closer to 350 miles. The tiny screen on the dash indicates I should get 370 miles or so after refuelling but at most I get 250.

So I think I’m getting about 17 miles per gallon.

MikeyH · Post by **MikeyH** » Mon Nov 27, 2023 6:26 pm

Flyer wrote: ↑Mon Nov 27, 2023 3:55 pm I had a friend with the same engine 5 series and he was getting closer to 350 miles. The tiny screen on the dash indicates I should get 370 miles or so after refuelling but at most I get 250.

So I think I’m getting about 17 miles per gallon.

Gulp!

Five-O · Post by **Five-O** » Mon Nov 27, 2023 6:34 pm

You realise a 5 series has quite a bit bigger fuel tank don't you. 68 litres compared to 55.

enuff_zed · Post by **enuff_zed** » Mon Nov 27, 2023 6:40 pm

Manual or auto/
My wife's 2.5i auto gives anywhere between 27 and 31mpg, depending how late she leaves the house!!!
Manuals seem to give better figures.
Even so, yours is extremely low.
Even overhauling the vanos seals only gave us an extra 1-2mpg.
One stupid question, but knowing how finnicky these zeds can be with refuelling (always clicking off early), are you sure you are actually getting a full tank?

Mr Tidy · Post by **Mr Tidy** » Mon Nov 27, 2023 8:49 pm

Hi and welcome to the forum.

That does seem thirsty, but it will always use more fuel this time of year and it depends how you use the car.

I had a 3 Series with the same 2.5 litre M54 engine and it comfortably averaged 30+ mpg during the 3 years I had it. But then 80% of my use was outside of rush hours on A-Roads and Motorways!

colb · Post by **colb** » Mon Nov 27, 2023 9:35 pm

My 2003 2.5 Z4 is used for short local journeys and the occasional longer trip going by the dash mpg display I see around 30ish but I do have a lead foot. Long steady trips will see the mpg in the mid 30's and more.
Always good to scan the cars live data and see what the fuel trims are doing, high trims can indicate air leaks or failing Maf sensors which would have a big effect on mpg. Maf's don't always set codes but will affect fuel trims. Live data is also useful to see how exhaust sensors are performing pre cats should produce a wave form in graph view as the voltage rises and falls, post cat sensors often look pretty static unless they are picking up unburnt fumes, codes would probably be set in the latter case.

Rsipad · Post by **Rsipad** » Mon Nov 27, 2023 11:10 pm

15-16 mpg here (N52 manual) with equal highway and city driving and a bi-weekly mountain run

Highest I've had was 38 mpg on the highway while going 55mph for 2.5 hours.

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