Onboard Mpg Computer Is Rubbish

[Johan007]

My on board computer says I only get 45mpg. I presume it is calculating MPG since the car was made!

I put in £46@£1.15 total excellium for my trip to Devon with my light weight wife and one small suitcase and reset the computer and did 455 miles. Only once or twice booted it and I drove it economically for 50% of the journey and the wife used the shift indicators when she remembered.

£46/1.15 = 40 liters

40 liters = 8.8 gallons

455 miles / 8.8 gallons = 51.7mpg B)

[haze20]

My on board computer says I only get 45mpg. I presume it is calculating MPG since the car was made!

I put in £46@£1.15 total excellium for my trip to Devon with my light weight wife and one small suitcase and reset the computer and did 455 miles. Only once or twice booted it and I drove it economically for 50% of the journey and the wife used the shift indicators when she remembered.

£46/1.15 = 40 liters

40 liters = 8.8 gallons

455 miles / 8.8 gallons = 51.7mpg B)

Blimey, what a difference !! What engine ahave you got ?

Any on else finding the same ?

[Johan007]

2.0 D-4D

[GregP]

I tkink that is quite common not only for Toyota. My compter always shows less than reality is, but the same is in my Golf and was in Toledo.

[Jock Fran]

How have you worked this out?

You say you've put in 40l and then driven 455 miles. How do you know you've used all 40 litres? Or how do you know you've not used 40 litres plus some that was in the tank before you filled up?

You need to fill up, drive x miles, then fill up again. Then the mpg is the x miles you've just driven divided by the gallons you've just put in.

If you've never reset your trip computer, and you've done a few miles, it will take a lot of driving to bring the overall average back up.

[Johan007]

Yes I should have said I re-filled at £46 that just happens to be almost same amount of fuel to one decimal place as I put in before the trip at 2 bars left on the fuel meter. 455 miles is not typical score as I usually trash it when I am not driving economically and only get 420 miles.

I reset both trip A and B... I must be missing to re-set something though.

[Jock Fran]

Resetting trip A or B won't do it.

You'll probably need to press the button that toggles through the average, current mpg etc.

When you're on the average, hold the toggle button to reset it.

That's how it works on my Corolla anyway!

[gpduffy]

also only gettin 45mpg ..... and ive reset the clock ... what is wrong with this car? i got 55 mpg on my corolla

[OldSkoO1]

the mpg computers are always bad if not reset regulary.

I find if i give my t180 some beans on a trip and it pushes it down to 36 - 38mpg it takes AGES to get back up again. Reset it and i get 45mpg; sometimes 50mpg.

You have to calculate manually for accurate results.

BMW's are normally the other way, over zelous.

[mpotter]

I reset the my average mpg everytime I fill up and generally only get 38-40mpg on a normal week commuting to work in stop start traffic in my 2.0D4D.

However, after a couple of long motorway trips over weekend my average is currently at 52.6 mpg (calculated over the last 380miles) which has come down from nearly 56mpg average (on the display) due to my commuting to work journeys bringing the average down.

My 2.0 D4D has nearly done 10k miles now and is definitely performing better lately on motorway journeys than it used to.

[gpduffy]

I reset the my average mpg everytime I fill up and generally only get 38-40mpg on a normal week commuting to work in stop start traffic in my 2.0D4D.

However, after a couple of long motorway trips over weekend my average is currently at 52.6 mpg (calculated over the last 380miles) which has come down from nearly 56mpg average (on the display) due to my commutting to work journeys bringing the average down.

My 2.0 D4D has nearly done 10k miles now and is definately performing better lately on motorway journeys than it used to.

does the trip not reset every time u refuel?

[mpotter]

does the trip not reset every time u refuel?

No, you have to press button till average is showing on display and then press and hold the button in until the reading is reset to zero. When I do this I also zero the trip A reading as well so I know what mileage the average mpg is being based on.

[Morrishey]

All the 'calculated' readouts on the trip computer needs individually resetting. Average MPG, average speed, running time etc. If you want to only know the figures for this tank, you'll have to do as mpotter says for each individual readout.

[rcflyer]

does the trip not reset every time u refuel?

No, you have to press button till average is showing on display and then press and hold the button in until the reading is reset to zero. When I do this I also zero the trip A reading as well so I know what mileage the average mpg is being based on.