A two+ hour drive would really take it out of me. I would often have to stop and have a 10 minute nap.
I’ve found meds have really helped, I still feel tired, but I don’t have to sleep afterwards or take naps.
Same with riding motorbike, but double. I think it’s the intense concentration for long periods of time.
Could be drowsiness inducing for you for sure, but in general generation 2 antihistamines are incredibly non drowsy. Only mention it because it is so fascinating. It took us like 30 years after finding Benadryl to find something that won’t put us to sleep.