If memory serves me right, you have to go to confession prior to receiving the ashes.
Maybe the Priest comes up to your car. I've gotten the sacrament before in my Catholic days, the confessional booth isn't NECESSARY, all you need is privacy. The Priest could hear your confession in a garage, a parking lot, etc.
It's a shame that the RC Church since the 90's has been getting more political & fundie. They used to be RELATIVELY moderate in a way...mainstream...sane...apolitical. I miss the days when Vatican 2 was somewhat followed. Much of the religious/mystical/ritual aspects I love & they did at least preach things like ecumenicism, charity & avoiding war (even if it wasn't always followed). Since Benny-Joe The Ratboy has been elected Pope, they've been going backwards! THE HELL WITH THOSE POMPOUS PATRIARCHAL, NEO-PHARISEE WINDBAGS & THEIR PEDOPHILE ENABLERS!
I think sane Catholics should just break away to more open-minded Catholic splinter churches! The Vatican lost it's soul LONG AGO. If they need a Pope, they got St. Peter! The guy in the Vatican is merely The Bishop of Rome, anyway!
Me, I'll be a Wiccan.