This may "need more work," but something along these lines seems worthwhile. A manufacturer might offer this as a feature, since it would require only a little (?) software programming.

It could also give a second-hand buyer an indication of how hard a car had been driven. (The original owner would have the option to erase the data, but if he was a careful driver and didn't do so, he would be able to get a higher price when he traded it in.)

I can understand the sentiment that you're trying for, I just don't understand 'engine miles.'. How about an hour-meter on a car? It would be so easy, I don't know why they're not already used.

With modern electronics, they could even break it down into graphs or something.

As for the fuel-economy meter, I've rented vehicles with them and I don't believe them now. Calculate your mpg the old-fashioned way and tell me if yours is right...the ones I've seen were very optimistic.

It is called an hours meter, used on commercial and industrial engines.and sometimes directly connected to engine rotation, like an odometer on an RPM gauge.

classicsat, I think you meant to say it's called a "Hobbs" meter.

On my plane it was on an oil-pressure switch, but on my lawnmower, it was just on the key. Leave the key on for a week and it looks like I mowed lots of hours...

On my 1957 Ford tractor, it just turns when the tach turns. I think the tach-based version is pretty interesting because it's recording actual engine revolutions, even if the hours are wrong based on the hour-meter. It assumes '1515 rpm'--which when I'm grading or mucking I'm only at 1000 rpm and when I'm mowing or plowing, I'm at 1900. I guess it averages out.

Nope, I meant hours meter. Hobbs is a manufacturer of them, typically in standalone units that may actually record the hours an machine is operated (in the case of an engine, often at a constant ideal RPM). Most of our equipment has an odomoter like counter in the RPM gauge, like yours.

One correction in the original post. Please read "These miles will increase if your car is idle with the engine roaring" as "These miles will increase 'EVEN' if your car is idle with the engine roaring".

The basic idea that I posted was not Hour Meter, which tells you the time an engine has been running. My idea of Engine Mileage is this:

Consider your car's engine rotates for 50K times in order to run a mile at the top gear, my car might take 40K rotations to do the same distance.

If I drive my car in the lowest gear, it will probably show 0.15 mile in the milo-meter but it would show 1 mile in the engine mile. If, in idle condition, my car engine takes 40K rotation in 10 minutes, it would keep increasing 1 mile per 10 minutes.

The idea is to capture a standard "If this car was ALWAYS running in the top gear, how many miles has it done?". While we know that, in fact, the car has actually physically moved just half the distance because i always drive on city traffic with a lot of obstacles - and I never touched the top gear.

This can simply help people compare engine conditions irrespective of usage type of the car.

Makes sense?

Honesty is the best yardstick. If you are cheated on the miles on yourcar you buy or want to sell, you will have to just live with it. Whynot have a small chip which will diagonise the carbon deposit ina engine and display in on the dashboard. The display unit andthe cable to the engine can be sealed and made tamper proof.