Re: Why?
I'm sort of surprised you don't have a 12v socket (is it a USB socket instead? It would be possible to hook it up by connecting it to the radios 12v feed, however, which would be accessible by popping the head unit out and splicing the cables - perfectly legit if done properly) but you will have an ODBII socket - all cars have been required to have them by law for nearly fifteen years in the UK, a bit longer in the US.
It'll be somewhere in the footwell/under the dash (more recent regs state it must be within something like 60cm of the steering wheel IIRC, and must not be hidden away behind anything with screws on it). Even my ratty old 2000 Ford Puma has one, and it can rattle of RPM data, water temperature, MAF airflow, estimated road speed (calculated from gearbox ratios and wheel size, same data the speedo uses), etc. although the update/refresh speeds on my car aren't that hot as it was an early implementation before consumer devices that use ODB info were commonplace - I think most modern ECUs are much faster to provide the data, and can provide more info at once (IE my car will update water temp, speed and RPM info in a serial stream of 1,2,3,1,2,3,1,2,3, with each updating in turn.
I've seen Torque used in more modern cars where it seems to have more bandwidth and the data all looks 'live' for all feeds, rather than clearly updating one feed at a time).
ODBII is very much a *read only* protocol without the right hardware attached to it, too - that's why a tuneup flash of your ECU over ODB (DreamScience, REVO, etc) costs £300+, and it's something you can just pirate; it needs special hardware that is signed against the ECU, I believe. So no-one will be setting off your airbags or disabling your ABS remotely any time soon.
That said, on the subject of the device itself, I don't see the need for it; if you're that tied to your social connectivity channels, then I'm firmly of the opinion that you need to reprioritise your life.
I like having an excuse for going for long drives as it means I can legitimately just turn the fucking phone off. That said, if it can push oil/water temp, oil pressure, and other measurements that aren't on the dash any more (but are still useful - pulling over and killing the engine can be done quicker and more safely when you see the pressure drop like a stone, rather than teh minute it might take for the engine to start clattering and potentially seize - taking out the gearbox/clutch with it) then I might be interested. As long as on my phone I can set my status to
'Driving. Fuck off'.
Steven R