But now they need to pay for the car anyway, so you're left balancing the comparatively small cost of parking + extra gas + extra mileage against inconvenience of switching transit methods + cost of transit.

There's many other factors, too, which could influence things in either way: total time spent commuting, whether you hate crowded spaces and prefer to sit alone in your car, whether you can be productive (eg: phone call, working on laptop, doing email on phone etc) or want to be able to read.