First off, my dad is NOT into motorsports.
I would like to go somewhere with fun things to do / see within about 6 hours of Summerville, SC.
My father is not the most active person any longer. No biking / kayaking / long hikes, etc.
We do like to be outside. We like history. We like museums. We like breweries / distilleries.
And.... Go!
There's a lot to do at the Indy 500 besides watch the race.
One year I went to the Indy 500 for two days and really didn't see the race. Factor in being 20 years old, my 7th year at the race, little sleep, Everclear with Koolaid out of a dudes milk jug, maybe a little ganja and .......well, you get the idea.
You're Dad enjoy hanging out with drunk, redneck ladies in their early 20's?
Asheville NC: 4 hours from you. Dozens of breweries downtown. The mountains. Somewhat cooler temps.
A 6 hour range from Summerville tends to keep you in the Deep South...
Obviously when i think museums, I think Washington DC... about 8 hours... too far, too hot to stroll.
In reply to Purple Frog :
seconded. Asheville is dope. Plus, the Biltmore is there (offers history/architecture/nice nature)
The SC State Museum in Columbia is pretty fun. https://scmuseum.org/
Ft Sumter and Ft Moultrie are a good way to spend some time locally. https://www.nps.gov/fosu/index.htm You can hit up the Charles Pinkney National Historic site in Mt Pleasant while over that way.
Patriots Point is impressive but plan a full day and there is a lot of walking and climbing of stairs.
There is also Hampton Plantation https://southcarolinaparks.com/hampton out in the national forest as well as Battery Warren https://www.fs.usda.gov/recarea/scnfs/recarea/?recid=47383. Both of those are off the beaten path.
The Biltmore in Asheville is pretty impressive. It's guaranteed to be crowded this time of year.