REQUEST: trip statistics in cars

Hi,
I like to know what the per gallon statistics are for my car. Just yesterday, filling up my car at the petrol station, I realised that the car manufacturers missed a trick with the trip mileage counter. Once the car is filled up I always wonder how I did driving wise. And not just from the current trip but from my last trip(s) as well -- since I usually reset the counter after filling up.

It doesn't take much computational power away from the systems to store the statistics. It also does only require a simple user interface -- simply displaying the mpg number at the same time as the mileage would do. Ticking once on the reset button goes back, keeping it down for 10 seconds resets the current counter.

The only slightly expensive affair is to measure the volume in the petrol tank more accurate. That can be done with weight sensors on the tank or some electronic capacitance [1] sensors. I would think the standard float based gauge will not be accurate enough.

There is a fairly straight forward thing to do. I wonder why there is no pressure on the car manufacturer to offer these kinds of statistics if they can help us to drive more consciously.

[1] http://en.wikipedia.org/wiki/Fuel_gauge