There are only a couple lines of code, but the strings are named "car_location", and they read "Where you parked". It can usually be tough to assume intent with code snippets, but those seem pretty easy to read. Google Now is already using your location to serve up reminders, travel information, and more; so, it's not too big of a leap to assume that Google would want to help remind you where you parked.
Android Police have found all there is right now, it may be a bit off, because it seems like it needs a bit more work.As usual with rumors like this, we can't verify exactly that this will be coming, but it makes sense. Also, we can't say exactly when the feature might hit, but assuming the code hounds at
source: Android Police