Stay OFF the dunes - always
Driving on or damaging the dunes is illegal (they're protected, and they're the coast's storm barrier - fines run $50 to $2,000 a day). Use marked crossovers only.
Coast / Driving & parking
Yes - you can drive on most Texas beaches. The hard-packed sand is almost like a dirt road, which is why Texas is one of the few places you can pull your car right up to the surf. But there are rules, and they're local.
A special case
The National Seashore is unusually open: no permit, no inspection, and no special equipment to drive the beach - your vehicle just has to be street-legal (regular plates, not ATV/OHV).
North Beach: North Beach is drivable by any street-legal vehicle - 2-wheel drive is fine.
South Beach (4WD): South Beach is tougher than people expect. Even in the first 5 miles, 4-wheel drive is recommended and may be required; past mile 5, 4WD is ALWAYS required. The deep-sand stretch called 'Big Shell' (around miles 17-28) strands unprepared vehicles regularly - don't push past your vehicle's limits.
The 'Closed Beach': The 'Closed Beach' - the roughly 4.5-mile stretch around the Malaquite Visitor Center - is closed to vehicles (walk-in only).
Beach camping: Beach camping is allowed on North and South Beach - it's included with your park entrance pass ($25 for 7 days, or a $45 annual pass), not a separate free permit.
Driving on or damaging the dunes is illegal (they're protected, and they're the coast's storm barrier - fines run $50 to $2,000 a day). Use marked crossovers only.
Speed limits are low - 15 mph in Port Aransas, and 15 mph on Padre Island - the first 2.5 miles of South Beach stay 15 mph year-round, and the rest of the beach rises to 25 mph from the day after Labor Day through February. Kids dart between parked cars and the water.
An incoming tide plus soft sand strands vehicles. Park well up the beach, don't get boxed in, and know your high ground.
Bollards (rows of posts) separate the driving lane from the pedestrian area on some beaches - park on the correct side and keep the lane clear.
Official sources
Beach parking permits come from the cities of Port Aransas and Corpus Christi; driving rules at the National Seashore come from the NPS. Permits and rules differ by beach.
Caution: Permit prices and beach-driving rules change and vary by beach. Confirm with the specific city, county, or park before you go - and never drive on the dunes.