Question: ab exercises you can do in the car?
Answer: The abdominal vacuum: “Exhale all the air from your lungs, then use your ab muscles to suck in your stomach, as if you were pulling your belly button back to your spine. Hold, then release. ... 
The Kegel: “Tighten and release the pelvic muscles … ... 
The glute squeeze: “Tighten your stomach muscles and squeeze your glutes.”