In no particular order…
Manually open doors under the dash for air circulation.
Sliding around on hot, sticky vinyl seats in summer. No seat belts, of course.
Keeping two or more gallons of water in the trunk while heading to the beach. Never knew if you would get stuck in bumper to bumper traffic and overheat (always did).
Installing a FM converter so I could listen to commercial free music. Set one AM station for this.
My dad would out his old wool winter army coat over the engine during cold spells when he came home from work to try to keep the heat in so the car would start the next morning.
Starting ether.
0-60 times measured with an hour glass. Dad didn’t believe in V8 engines. Probably kept me alive when I started driving.
This thread is a lot of fun, but sure takes the nostalgia out of our older cars. But it was very satisfying being able to tune up the car yearly and change the oil every 2k miles.