[rfdesigner]

I would like a scangauge but they say it's not compatible with my car (Boooooooooooooooooooo!!!!!)

However I'm an electronics R&D engineer.. and these sort of devices are bread and butter to me.. so I've been thinking about the details of how they work and realised they (to my knowledge) miss a trick.

When doing P&G people are still kind of guessing about the P.. is it 60% throttle, is it 85%.. have a play.. 80% seems better, but it's all 'have a play'.

What occured to me was that the MPG calculation could invlove an intermediate stage that would allow us to see just how efficient we're really being.

The idea is to include an accelerometer. This would be used to calculate the vehicles acceleration or deceleration. Knowing the vehicles weight the gauge can then

A: work out the gain or loss of momentum.

B: work out the energy efficiency of the engine.

C: work out the energy consumption of pushing the car along.. to produce the mpg figure.

So.. during the pulse phase, or going up hill, it notes we're gaining potential or kinetic energy.. it keeps a note of that, and makes its estimate of the engine efficiency.. lets say it's 25%.

When coasting it can see the loss of momentum over time, if you're going slightly downhill, it sees that with the accelerometer and accounts for it.

The bottom line is it ought to be able to work out your rolling resistance and your coefficient of drag.. at least over time.

It would also allow the gauge to put up really really BAD figures when you hit the brakes.. which is more honest I think.

any thoughts?

Derek