I don't have a car, so that's not an issue.
If I got mugged or attacked... Well that could be a tricky one to explain I guess.
Such a thing has never happened to me though. I guess I'd just try to put it like I was on the way to work, going for walk, going to the gym, or going to a friend's house. Could cause issues if she was to try and varify things I suppose. Don't give her ways to easily track you I suppose is a pertinent point. Switch all that tracking bollocks on your phone off.