Why would you want it on your cell phone? That information is available on the instrument gauge system, which is much safer to monitor than a cell phone.

Two important parameters which need to be monitored constantly, you lookat the cellphone more often than the guages on the dashboard

Maybe you look at the cellphone more often than the gauges but I am constantly doing a quick scan of the temps, pressures, and fuel usage.

I highly suggest dumping the cellphone while driving. . . .

If you want to develop your own cell phone applications, you can do so for free using Google Android:

Google Android

Whatever your mind can rationally perceive within the constraints of a cell phone, you can make it happen.

I could see making this application available on the cell phone so long as the cell phone is not moving faster than 5 mph; thus ensuring the driver is not distracted while driving.

Also include other functions like ensuring the doors are locked, tracking the vehicle when the kids have the car, tracking the vehicle if it is stolen, providing continuously updated maintenance records, providing a maintenance schedule to get the most out of a vehicle, incorporate vibration sensors in the motor to characterize impending failures, a national database for roadside assistance, ....