There are a fair number of tuning link / software packages
out there for OBD-II and CAN bus automotive control systems,
I believe I've seen one wireless but that is only for the vehicle
data link as a dumb slave.
You'd be looking for something to assert the PIDs of interest
and stream them to a portable device in its format, which is
not going to be simple; a PC host would be a lot easier.
There are some open-source vehicle interface projects
going on out there. I forget their acronyms. ELM maybe?
"open source obd2" returns a tone of Google hits (unless
you're in China, I guess).