Automatic (YC, I think) do a good amount of that driving analysis, like telling the driver they brake or accelerate too hard, using only OBD-II and an accelerometer.

I think a built-in system doing this kind of thing would be really cool. The technology is obviously already there, but the software isn't, so having an app platform creates a lot of opportunity. I wonder how deep Google will be able to convince manufacturers to take the integration - modern cars expose a ton of data and functionality over the CAN bus, but it's all undocumented and proprietary and is often obfuscated as well.