Does my MPG seem low?

Negotiator

Currently driving a Micra 1.2 auto 2006. I do a 7 mile round trip a day to work (lazy I know), 5 days a week. Generally a full tank of fuel, costs about £40 and lasts 4 weeks, 129p/litre. This is from the needle is at the top of the fuel gauge to just past when the fuel light comes on. Ive worked it out and it seems like I am getting about 21MPG or 144miles for £40 of fuel. Am sure some hot hatches get better MPG than me, something must be wrong.

Mankysteve

To work out your millage properly you need to brim the tank(ie first click on the pump) reset your clock. and then refill again and then do the math(there plenty of calcs online to do it for you).

This will give you a real idea of your millage is.

gpc273

Your commute is fairly short, so the engine isn't heating up to its optimum temperature for max fuel efficiency.
This will have a major effect on your mpg, plus the fact most auto's are nowhere near as fuel efficient as manual.

InsideInsurance

Not an expert on these things but our 4.6L auto car does almost 30mpg even without sensible driving at times.

What sort of journey is your 3.5miles? Stop start through town? Free flowing dual carriageway?

First of all measure it a little more accurately as suggested above and then recalculate your MPG. I suspect the fact it is a short journey is not going to be helping your MPG as petrol cars always are less efficient when not up at normal operating temperature

Weird_Nev

You have basically combined several of the factors that will really hurt fuel economy:

Repeated short journey (this REALLY hurts fuel economy).
An Auto box - particularly with a small engine. Hammers fuel economy.

IF you want to increase fuel economy, I'd suggest cycling to work as often as possible - 3.5 miles is the ideal distance for this. Take the car on longer runs, to allow it to heat up properly.

Since your usage cycle is punishing, I'd recommend that you service it more frequently - every 6 months. Of course, if you use it less, you could push this out to 12 months.

Check tyre condition and pressure too, and if you notice uneven tyre wear patterns get the tracking checked and adjusted.

But really, using an auto car with a small engine for 3.5 mile stints will return you very poor fuel economy. There's not much you can do about that.

reddwarf2002

Seems to be really poor MPG even for an automatic. Remember owning an 1.8 Automatic which did 30 MPG on very short runs so you should be aiming for atleast 28 MPG.

I would get the car checked out if I was you. First thing to check would be to scan for fault codes. You can also check the brakes and make sure it's not binding/sticking which would affect MPG.

forgotmyname

3.5 miles with the car overfuelling to help warm it up. There is the issue.

Dont you use the car for other journey's? Just to work and back 5 days a week? I think you maybe covering more miles than you realise.

Does the fuel needle drop off the full mark fairly quickly? You seem to be putting approx 31 litres into a 46litre fuel tank. So still room for another 15 litres or there is still 15 litres left in there.

Fuel gauges are not totally linear in movement. They may move more at different fuel levels than others.

Mine moves slowly off the full mark, But just above and below 3/4 it moves quickly then stabilises again until it gets to 1/4 when it drops quite quickly.

Reset the trip and note the mileage when you next fill up and work out the distance. Make sure the 2 figures add up.

gabbleRatchet

I'd say it's too low even for an auto doing lots of short trips.


My wife has a 1.4 Micra auto 2008 and mostly does lots of short trips with maybe one 40 mile round trip per week. I've never calculated exactly what MPG she is getting but the readout on the dash generally says between 30 - 32 MPG.

facade

If you want to throw money at it on the off-chance that you might catch the fault: change the pre-cat lambda sensor (nearest to the engine), this one controls the mixture and causes low mpg when it starts to go bad.

Weird_Nev

facade wrote: »

If you want to throw money at it on the off-chance that you might catch the fault: change the pre-cat lambda sensor (nearest to the engine), this one controls the mixture and causes low mpg when it starts to go bad.

That's a good point, but a garage can check this very easily to see if it's failed.

yangptangkipperbang

facade wrote: »

If you want to throw money at it on the off-chance that you might catch the fault: change the pre-cat lambda sensor (nearest to the engine), this one controls the mixture and causes low mpg when it starts to go bad.

No point in doing anything until a more accurate mpg figure is arrived at.