Petrol usage question/advice

freddie_2

I have started keeping track of filling up with petrol.Its 50 pounds a week but this only does me for school runs and day to day taxing of DD to groups etc. No big trips as I can't afford the petrol.
Last week I filled up and mileage showed I had 260miles of driving. Light came on tonight and no miles left to drive. But the millage counter said I ad only driven 206. Where. Has the other 54 miles worthgone?

Is it doing short journys or is it a fault in car?

Any ideas?
Sorry for awful typingi am on phone.

Weird_Nev

Short journeys.
Most cars get about 2/3rds or less economy during slow town or stop/start driving compared to the open road.

If you really want to work out your MPg, which is much more usedul than miles to the tank or miles to £20, then:
Fill up until the pump clicks once.
reset your trip counter.
Drive.
Re-fill until the pump clicks once.
Keep the receipt and mark it with miles covered, then re-set the trip counter again.

Now do some maths: Mpg = (Miles covered) divided by (litres used divided by 4.55)

This will give you a fairly accurate idea of your cars Mpg over the tank of fuel you've jsut used, and you can compare that to the type of driving you've been doing.

freddie_2

Thanks. Never really paid attention topetrol usage before but really. Have to now. Its so expensive. Will try to work out MPG.

Weird_Nev

yup. And trip computers tend to lie, especially if you are doing short journies, so it's useful to know what you are actually getting for your money!

closed

light should come on before 0 miles left to drive, usually 50 or so left.

daveyjp

Distance to go is a constantly changing figure based on current mpg and fuel in tank. Last week I started out with 60 miles to go, did a few miles at 50 and it had gone up to 90 miles, I then had to slow and by the end of a 12 mile trip it was at 55.

reeac

Weird_Nev wrote: »

yup. And trip computers tend to lie, especially if you are doing short journies, so it's useful to know what you are actually getting for your money!

Why do trip computers lie for short journeys??

vikingaero

One thing that will really whack fuel economy is the recent cold weather. The engine will run rich for longer and there will be demand for juice from the lights, aircon, rear window demister etc.

scheming_gypsy

Weird_Nev wrote: »

Short journeys.
Most cars get about 2/3rds or less economy during slow town or stop/start driving compared to the open road.

If you really want to work out your MPg, which is much more usedul than miles to the tank or miles to £20, then:
Fill up until the pump clicks once.
reset your trip counter.
Drive.
Re-fill until the pump clicks once.
Keep the receipt and mark it with miles covered, then re-set the trip counter again.

Now do some maths: Mpg = (Miles covered) divided by (litres used divided by 4.55)

This will give you a fairly accurate idea of your cars Mpg over the tank of fuel you've jsut used, and you can compare that to the type of driving you've been doing.

easier way is to stick the details in http://www.torquecars.com/tools/uk-mpg-calculator.php and let it work it out for you.

forgotmyname

Can you reset the fuel trip? Most probably have never been reset since new.

The 260 is the computers guess at average mpg, The school runs are using more fuel so the average drops.

If you jumped on a clear motorway and cruised at about 60mph you make cover 50 miles and still get the trip
showing 260 miles left.

26mpg fairly normal for a car doing mainly or only short journey's.

I do mainly short journeys and took a trip to blackpool one day, I covered almost 100 miles before it dropped below
the estimated distance left when i started the journey.

100 miles for free.