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Driving is the most common way to reach a campsite. You camp in a campsite.
If you set up a campsite off the hiking trail you are backpacking.
Apparently there are autists who consider setting up a campsite while backpacking "pure camping" but as another anon has said, that is not what your average person does.
They drive to their site and camp in the campsite OR in OP's case they camp in their car. Thus car camping