I think some people would like this, but mostly I think of phone calls and letters from auto-places as an annoyance because I do pretty much all of my own car-work.

Dealers might like this because the car would be delivered with their own phone number programmed into the automatic-sms phone number. But I think most people go to a tire place for tires, a oil place for oil, etc. So will the car know which place to text?

Also, the car at present doesn't really have a way to moniter the freshness of the oil, the coolant, the transmission fluid, brake fluid, and tire tread. So either you'll put a requirement that these changes be entered into the car's computer by the technician--at $60/hour--or you'll just have notices that go off at regular intervals, then hopefully turn themselves back off.

Our first VW had an EGR light that would just go-on for no reason other than milege, then a 'technician' (me) would have to push a button under the hood. It was stupid. Yes, I checked to make sure the EGR pipes hadn't fallen off or something...

Yes, I really think you'll need to solve the self-diagnosis problem first. Has that been a why-not?

Modern engine computers can self-diagnose themselves to a certain degree, more than they could in the past, and with an appropriate communications device, report engine status to a central collection point, whom may be able to make data available to various service depots, or even the owner.

classicsat, I agree that when something is wrong, the engine computer can often tell (or it gives you cryptic information that even your mechanic doesn't understand), but the word 'service' implied to me that he wants to be able to get your data to the shops even when your car was still running with no problems of failures.