how many mpg?

ali-t

In the absence of a maths board I am seeking feedback from any of the MSE'ers who can count. In the spirit of this board the question is in relation to fuel economy.

My car doesn't have a button that tells you the mpg when you are driving so I have filled it up from when the red light came on and checked the mileage when the light came on again. I had to do a refuel mid-count due to a long journey but the figures I have are:

65 litres of petrol did 450 miles.

I am trying to work out the mpg and how much each mile I travel costs me but am struggling with the maths side of it.

I worked out that 65 litres is 14.2 gallons and 14.2 gallons divided by 450 miles is 31.6mpg.

How do I then work out how much in pence (or pounds) each mile costs me?

I am hoping this will give me an MSE jolt to leave the car at home more often but I can't work out how to get the answer.

vaio

divide the cost of a gallon of petrol by your mpg figure

redpete

or take the cost of that 65 litres and divide by 450.

It'll be something like 17 pence per mile.

redpete

or take the cost of that 65 litres and divide by 450.

VoucherMan

Since the op is looking for a reason to leave the car at home would it be worth factoring in a 'wear and tear' figure into the cost per mile?

I used to work with double your fuel cost, or 20p/ mile but I've no idea what it would be now days.

ali-t

Thanks for the replies, I have no idea how I have done it but this is a duplicate thread.

iolanthe07

I wouldn't go by the red light. These are notoriously variable and unreliable and can be influenced by all sorts of things like hills and sharp bends. Just do fill up to fill up over a month or so of mixed driving, divide the number of litres you have bought into the mileage and then divide the resulting sum by 4.45 to get the MPG.

sebdangerfield

iolanthe07 wrote: »

I wouldn't go by the red light. These are notoriously variable and unreliable and can be influenced by all sorts of things like hills and sharp bends. Just do fill up to fill up over a month or so of mixed driving, divide the number of litres you have bought into the mileage and then divide the resulting sum by 4.45 to get the MPG.

The light's got nothing to do with it. The only variables in the op's calculations are the distance covered and the amount of fuel used to do it. When the light comes on doesn't come into the calculation. The ops done it right.

pompeyrich

sebdangerfield wrote: »

The light's got nothing to do with it. The only variables in the op's calculations are the distance covered and the amount of fuel used to do it. When the light comes on doesn't come into the calculation. The ops done it right.

It does in this case, as the op is using the red light as a point of reference. they put 65l of fuel in when the light came on and assumed when it came on again the 65 litres had been used but as iolanthe07 said the light is not always going to come on at the same fuel level.

calleyw

try here.

Works it all out for you :T

Yours

Calley

sebdangerfield

pompeyrich wrote: »

It does in this case, as the op is using the red light as a point of reference. they put 65l of fuel in when the light came on and assumed when it came on again the 65 litres had been used but as iolanthe07 said the light is not always going to come on at the same fuel level.

But he doesn't. And he didn't. He's done it the proper way, work out how much fuel it used to do x amount of miles. Not, as you make out, estimate how much fuel the tank holds then use that to work out the MPG, wholly inaccurate. He said;

My car doesn't have a button that tells you the mpg when you are driving so I have filled it up from when the red light came on and checked the mileage when the light came on again. I had to do a refuel mid-count due to a long journey but the figures I have are:

65 litres of petrol did 450 miles.

He hasn't used the light as a point of reference, he's just filled it up when the light's come on. i.e from an almost empty tank, then filled it up some more for a long journey and added the amount of fuel put into the vehicle together, there's no guessing when the light comes on involved. That bit where he said he did a refuel mid way for a long journey should prove that. He put in a total of 65 litres, that's the point of reference. The light's got nothing to do with it.