Drop In Yaris Mpg

[brayn99]

Hi, I have an 11 plate Yaris 1.4 diesel. I was getting a steady 61/62 mpg until I last filled the tank (not from a supermarket) when it dropped to 53/54 mpg. No noticeable change in performance. Anyone got any ideas what might cause this drop before I take it to the garage?

[Madasafish]

Winter

[Lustral]

On my SR I was getting about 45-46 MPGs, thats in summer. But now on the last refuel I got 37MPGs ... Yup winter bites fuel economy

[brayn99]

I have to confess to some amazement at this. I suppose I've never had a read-out giving fuel economy before and so have never been that bothered about exact mpg. Thank you for your comments and help, both brief and enlarged!

[Mountain Rover]

I've kept a complete log of mpg since buying my Yaris D4D in 2007. Unfortunately it went AWOL when my PC crashed last year. I know I was getting over 70mpg overall in the first five years, sometimes in the high 70s. However since last February when I had the car serviced by a local independent the mpg has gone down to mid-high 60s (that's over nearly a year, not a one-off recording). I'm lucky if I can get 68 now between fill-ups. Needless to say I shall take it back to a Toyota dealer this year. I didn't want to take it back to the independent but I wonder what they did or didn't do? Part of the service was fuel filter replacement. Perhaps they used the wrong type or didn't fit it properly (though I've not been aware of any fuel leak).

[Cyker]

Tricky... fuel filter is usually more gradual.. I suspect it may be oil - My one is noticeably more sluggish on, say. 10W40 than 5W30.

[butt01]

I have had a 2009 Yaris SR 1.33 (petrol) for three years now - my mpg has always been between 26-28mpg (winter/summer) - is this bad and hiow can it be improved.

It gets serviced every year with Toyota oil and filter. I haven't replaced the spark plugs yet and Toyota tell me that you cannot replace the fuel filter as it is fitted next to the petrol tank.

Tyre pressures are set to 32psi all round.

Thanks

[Mountain Rover]

Tricky... fuel filter is usually more gradual.. I suspect it may be oil - My one is noticeably more sluggish on, say. 10W40 than 5W30.

Thanks Cyker.

When I take it to the Toyota dealer in a few weeks I'll mention it and see if they can solve it.

[HowardL]

Going by the fuel computer, mine says 41.5mpg,....1.3 CDX 2003

I've done an aifilter and plug change a week or so ago

I am logging my mileage and litres of fuel over the weeks so will get a more accurate figure.

The computer was reading 44.5 mpg before I reset it a couple of yrs ago.

[Cyker]

Hmm, my last tank clocked in at 55mpg, vs 60mpg and 63mpg previously so may also be a weather thing??

(V-Power diesel experiment still going!)

[Madasafish]

I reckon winter losses at 15% - based on the past 7 years.

On petrol cars about the same.

[butt01]

Does this mean that 26-28mpg is very low. The car has only done 18k and is serviced every year - oil/filter changes. I haven't had the spark plugs changed since I have had the car - should I change these even if it's only done 18k. The car is driven locally most of the time for school runs etc.

[HowardL]

Does this mean that 26-28mpg is very low. The car has only done 18k and is serviced every year - oil/filter changes. I haven't had the spark plugs changed since I have had the car - should I change these even if it's only done 18k. The car is driven locally most of the time for school runs etc.

My opinion is, yes,

I'm no expert but I think it should be at least 35-40.

My 1.3 does local trips 90% of the time.

[Madasafish]

If you do very short runs and the car never really warms up, chances are the entire engine combustion chambers annd exhaust are covered in carbon.

You need a longish run 30-40 miles at least at 3,000rpm plus to clean it out.

(An Italian tuneup). And if it then improves do that at least once a month.

(I drive my wife's car once a month to do just that)