I'm only 52, but watching my parents age, and friends parents, it really varies from person to person. I know a 77 year old pilot, that I'd have no concerns hopping into a plane with him, but my mother in law at 79, I wouldn't let her drive around the block, and she thinks she is fine.
The fact you are concerned, is a good sign. Do you have a child or friend that would ride with you in a car or RV, and give you an honest opinion??
Maybe you can travel, and pick less congested routes, or maybe a smaller coach.
With the urge to go, I hope you can find a solution to let you travel, and enjoy your retirement!