How do computers on bikes/cars work out fuel economy?

I don't know how these things work, but you'd think if it knows how much fuel you've used (it has a fuel gauge after all) and it knows how far you've travelled (it's got an odometer too), the MPG's a pretty easy calculation.

Not suggesting it uses the fuel gauge and odometer, but the ECU obviously has access to these kind of figures.

Also if the speedo overeads, the mileage will correspond. So the car thinks it's travelled further, so the MPG figure will be artificially high?

Nice thought actually - my pointy overreads by a full 10% so it's actually only done 10350, not 11500 miles

I thought only speedo's over-read, not odometers? Have heard that several times, though I'm not sure how they do it.

Originally Posted by hovis

see sig

I get about 50 mpg

Sweet!

Matt