It's inevitable that your dog will find his or her way into your car at some point for vet appointments or trips to the park. The easiest way to remove dog hair from your car (or any other upholstered surface) is with a cordless or handheld vacuum. Opt for models that have mini-motorized tools designed specifically for covering smaller spaces and delicate fabrics. Swap in a crevice tool to get into edges and cracks where hair and crumbs from treats may have accumulated.
If you have any lingering strands, try smoothing a rubber glove across the seats or creating static with a balloon to get hair to cling. Good ol' duct tape is a good hack, too, as is dragging a squeegee blade across the seats for very satisfying results.