After How Many Miles Driving From A Full Tank Does Your Fuel Needle Move ?

[Fastlife91]

In my last petrol car which was bad on fuel economy I would fill the tank and the needle wouldn't move until I'd drove about 60 - 70 miles.

On my current car, 1.8 TDCI mk2 focus , I notice my fuel needle begin to fall from a full tank after driving only about 30- 40 miles and that is when I'm driving very very carefully, anticipating road ahead, accelerating gently, braking gently, driving slower.

and I'm very lucky if I can drive 180 miles before reaching half fuel line and out of a full tank if I drive very careful I may reach 350 miles !!!!!!!!

Why is it nowhere near the mpg statistics ? the written mpg for my car is

urban 39.2 mpg

extra urban 63 mpg

combined 52.3

and I only seem to be getting around 350 miles !!!!!!!!!!

M

Y CAR IS DIESEL AND 1.8, 2006 MK2 FOCUS SPORT, WHAT THE HECK IS HAPPENING WITH MY FUEL ECONOMY ?

[MONDEO TXS 2.2]

No car that I know of achieves the manufacturers stated mpg in real life, so you'll be very lucky if you do

Fuel economy is affected by so many influences, tyre pressures, ambient air temperatures, type of fuel, engine condition, turbo efficiency, oil type, injector condition, compression ratios, etc, etc

When was your fuel filter last changed ?

[Fastlife91]

No car that I know of achieves the manufacturers stated mpg in real life, so you'll be very lucky if you do

Fuel economy is affected by so many influences, tyre pressures, ambient air temperatures, type of fuel, engine condition, turbo efficiency, oil type, injector condition, compression ratios, etc, etc

When was your fuel filter last changed ?

Car is a 2006 mk2 focus 1.8 DIESEL

Fuel filter I think was replaced several weeks ago

Car fuel tank capacity is 52.3 litres

Wires to my maf sensor are worn, could that cause poor mpg ? Engine light on and code reads maf circuit a open

Had leaking injectors a while ago, not leaking anymore but code, injector circuit malfunction

. can't hear turbo, not sure I did when I first bought the car but I could hear a slight whistle on idle when I accelerate but can't hear that anymore and recently I can hear a whine when accelerating hard. My friend replaced turbo bearing several months ago but he got the bearing from a salvage yard

Can a turbo bearing be replaced singely or must a whole new unit turbo go on ?

[Russ]

Google how are mpg figures achieved and you'll understand why you will never achieve the stated figures!

[MONDEO TXS 2.2]

A correctly functioning M.A.F. sensor is essential for decent M.P.G.

[Fastlife91]

A correctly functioning M.A.F. sensor is essential for decent M.P.G.

Can you please provide answers to the questions I asked above, all of the questions.

Regards

[Preecematt]

I know how you feel, my average speed is 31mph and my average mpg is 33.2. I get less miles out of this than I did my last car and that was modified, had a bigger engine, 160,000 miles AND was faster lol. Do I drive like an idiot, no. I'm VERY lucky if I get 350 miles out of a tank. I let my car warm up before I move and my work journey is 3.1 miles... It uses 17 miles of fuel lol. I'm pretty sure if I asked for a discount at my local Shell I'd get one lol. But to answer your original question, work and back from a full tank and the needle has moved about 2-3mm

[AdeMk1]

Maximum mpg is achieved at a constant speed with very few variations, all the stop start traffic, sat idling at lights and speeding up & slowing down does nothing for your mpg, in fact if your commute is only a few miles a day you would be better off with a petrol car. Diesels are more efficient on longer journeys. Manufacturers mpg figures are plucked out of thin air, I know of nobody who gets close to the claimed figures.

[Stoney871]

I used to get over 420 miles from a tank on my mk2 Sport TDCI around town and over 500 miles if motorways were involved.

A duff MAF will definitely skew fuel economy.

You have to remember that economy stats are achieved on a bench with all variables as close to optimum as possible (temperature/airflow/fuel quality etc).

The figures only represent what manufacturers achieve not what is applicable in the real world.

Always take the quoted stats with a hefty pinch of salt.

A good engine clean ( e.g. Terraclean ), a healthy MAF, high flow air filter, a junk free boot, correctly pressurised tyres and all mechanical parts in good order will help to get the best mpg you can.

[Fastlife91]

I used to get over 420 miles from a tank on my mk2 Sport TDCI around town and over 500 miles if motorways were involved.

A duff MAF will definitely skew fuel economy.

You have to remember that economy stats are achieved on a bench with all variables as close to optimum as possible (temperature/airflow/fuel quality etc).

The figures only represent what manufacturers achieve not what is applicable in the real world.

Always take the quoted stats with a hefty pinch of salt.

A good engine clean ( e.g. Terraclean ), a healthy MAF, high flow air filter, a junk free boot, correctly pressurised tyres and all mechanical parts in good order will help to get the best mpg you can.

Thank you.

I realized something last night and I wonder if this is probably the cause of my lower than expected MPG ?

In with the paperwork when I bought my car was the advertising form of my car from autotrader.co.uk, under technical specifications it reads my fuel tank is 52.3 litres.

Anyway, I went to ASDA last night and the fuel needle was only about 10 miles to half way so thought I'd fill it again to the brim, it ended up costing £19,02 from very almost half way to full to the brim and when I checked how many litres it shows only 17.83 ltrs ??

As it was basically almost touching the half way fuel line I'd thought I'd have used around 26 litres, but no. checked at the pump and on my receipt and only 17.83. so how can that mean the other half has 34 litres remaining ?

So according to last night's reading , I'd traveled 185 miles, around 70 % urban and 30 % short motorway ((driving very lightly on the accelerator and braking )) trips and several dual carriageway journeys until the fuel needle was almost half way on fuel costing £19.02 which definitely seems more like the economy I should be getting but I don't understand why at the very almost half way on fuel it only takes 17 litres to fill and not 26 ?

no wonder I was thinking I was getting poor mpg! what could be the cause ?

[MONDEO TXS 2.2]

This anomaly could be caused by a sticking / faulty fuel sender / sensor or a iffy fuel gauge, assuming the fuel tank is indeed the standard 52 litre fit & not a replacement as you have queried before

[Stoney871]

Could be a problem with the fuel level sender in the tank.

[Stoney871]

Beaten to the punch ;)

[MONDEO TXS 2.2]

Also bear in mind that generally the higher the engine mileage, the more worn the engine will be, & the mpg will decline accordingly

[ian1gail]

My gauge moves after about 60 miles from fill up. Although I do around 450- 500 miles before I fill up. Around 45 mpg with a mix of town and b road driving. Interesting about the capacity of the tank. I thought it was 55 liters so I have been running with less in than I thought towards fil ups.

[jmurray01]

After filling the Primera with a full tank (1.8 petrol) it can go 60-70 miles before it goes below the full mark, same with the 2000 Focus (also 1.8 petrol).

If your MAF has an error then that will be the problem, no doubt about it.

With regards to the accuracy of the fuel gauge, have you tried driving until the needle goes into the red and filling then? Once into the red it should only have a gallon or so left so should require at least 45 litres to fill to full.

[MONDEO TXS 2.2]

I mentioned the M.A.F. issue eons ago & also how to measure the fuel tank capacity , , ,

[jmurray01]

I mentioned the M.A.F. issue eons ago & also how to measure the fuel tank capacity , , ,

Indeed you did.

[MONDEO TXS 2.2]

The scroll up / down feature is useful I find . . . .