I don't have a car, but I am able to transport my bike on my motorbike. The whole process of taking it apart and tethering it is a bit of a faff so I don't do it too often. But even so, It's nice to have the option of going somewhere new and exploring, without having to lose the first and last portions of the ride cycling to and from the intended start point.
For example, sometimes I might fancy a ride along the coast somewhere. But to find any proper coast, I'd have to cycle for a good 90 minutes or so from my house to find it. So that's at least 3 hours gone just to get to and from the start point.
I'm not sure I'd bother transporting my bike just 4 miles to the start point like the OP does, but then if you're in a car it's much easier, so why not I guess.