Is there a problem with my car?

I am not sure if I am complaining about nothing but over the last 4000 miles I have averaged 51MPG, most of which has been at 65mph on the motorway. This is with me putting the car into neutral when going down hills and easing off as I go up hills.

I have TorquePro App and I was looking at boost pressure and when I accelerated heavily I the engine made 20PSI of boost. Tyre pressure is about 35PSI (2.4bar) with 225/45 17 tyres. I have very little rubbish in the car and fill up to max every time (to monitor fuel consumption).

The engine is remapped but obviously it should only use more fuel if I accelerate more quickly. The engine timing is also "perfect" according to VCDS. I have heard that advancing the timing can improve fuel consumption but I am not sure how much to advance by, what the gain would be and if it can cause damage.

Am I being paranoid, could I get the MPG higher? I was hoping for more like 56+MPG average.

The MPG will drop as the weather gets colder - a number of factors cause this (denser air, engine takes longer to warm up, fluids are more viscous).


What year is your car?
Does it have a diesel-particulate-filter?
How long is your average journey length?

It does take about 10 miles to warm up to 90 reading through my phone.

Its a 2002 1.9tdi ve engine 110hp.

Journey time is about 45 minutes.

>Its a 2002 1.9tdi ve engine 110hp.

Well, that's pre-DPF (which is good), and the 1.9 engine (which is also good). A reasonably long drive should also be enough to let your engine warm up, so that's good too.

Presumably your MPG figures are UK gallons rather than US gallons? If so, your mpg does seem a bit lower than I would expect, even taking into account the recent cold. Perhaps your turbo would benefit from an 'Italian tune' to shake off any soot which has built up on the vanes. Once your engine is fully up to temperature, drop down a gear on the motorway & floor it briefly (say 30sec to a minute), preferably up a long hill. If you see black smoke in your rear-view mirror then that indicates that soot has built up in the system. Repeat until there is no black smoke. Obviously that will use extra fuel, but the following tank should hopefully improve. I used to do this every 2000 miles or so when I was running my 1.9TDI.

The other thing which could be causing it is your tyres ... 225 tyres have a wide contact patch & therefore more rolling resistance. Also, 45 profile 17s would have a bit of an impact compared to running taller 16s. Sure, tall narrow tyres aren't very sexy compared to wide low profile tyres, but do offer MPG advantages

If you already converted the MPG figures to US gallons, then 51mpg is reasonable at this time of year.

Hi,

Thanks for the reply. Yes I am working in UK Gallons. I will try the up hill pull, being in Devon there are plenty of large hills. Saying that, I know the hills will effect my fuel consumption but I do try and accelerate before an up hill section and then coast down the other side.

I am also running a healthy amount of injector cleaner/cetane booster (Millers Diesel Power Ecomax) with each tank (sainsburys fuel).

Could you block off the front grill ? This would get the engine up to normal operating temperature a little faster.

Will I not then need to pull over and remove the blockage once warm to ensure the engine doesn't over heat?

aymen_a22 said:

Will I not then need to pull over and remove the blockage once warm to ensure the engine doesn't over heat?

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Shouldn't be a problem as long as you are cautious- try blocking a small part off first, then build up.

Italian tune up complete. I have not blocked the vents off as its only been below 0 degrees C once so far and by the time I head home it is more like 10C.

Average fuel consumption is now 54mpg (UK) which I am happier with but still not great.

Any further tips?

You can install a heater so your motor starts up warm and doesn't spend any serious time getting to operating temperatures.

Frostheaters in the uk are kinda overkill (and pretty hard to find in 230v also!)

I would try blocking off at least part of your grill and see how that goes, theres a thread here somewhere explaining how to do it with pipe insulation. I've partially blocked mine using stuff called Correx (its what they make estate agent signs out of) off ebay. Marvellous stuff the fact that its not frozen here yet doesn't negate the mod, anything under 10c will see a benift

You could also try increasing your tire pressures a little as they seem pretty low. Its subjective as to whether it improves milage but I fell it does. Just do a few psi at a time, if you feel a change in the car then drop back

Cheers for the help guys. I will definitely block up the grill and stop using Sainsbury's fuel.

FlyingFin said:

Change your fuel!


Sainsbury's fuel has the lowest calorific value of all supermarket fuels

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Can you substantiate that statement? Only curious as I work almost exclusively in oil transport terminals and watch tankers for Shell, Esso, Sainsuburys, Murco, Morrisons, Tesco, etc etc etc fill up from the same storage tanks hundreds of times a day. The base fuel is identical with the only difference being additives. Shell have a specific additive, the rest use the same additive in varying quantities although the variation is fairly minimal. From memory morrisons add the least out of that list (although my memory is not the best!)

Personally I use either Esso or Tesco as both are on my normal routes and I cannot ever see a difference in milage between the two (I use GasCubby to track it as you can log what fuel you've put in). I also pretty much drive the same route at roughly the same times.