There was a time in my late 20s and early 30s when I could do 400+ a day or maybe 2,000+ over 5 days if trying some overambitious itinerary, which I did on my first and 2nd trip out west in the late 80s (LA, Las Vegas AND San Francisco? no problem!) and Northwest in early 90s (Portland, Seattle and Coeur d'Alene? No problem!). I'd take the extra driving hours out of sleep time to have at least some time at the destinations. If memory serves, I ended up renting from Alamo a good bit and often got Chevy Corsicas as the car.

Those days are gone. Nowadays 250 miles/day seems a bit much, I get tired a lot more easily if sitting for too long (have to use the rest areas), and of course gas is a lot more expensive. In some cities if you plan ahead and max out coupons you can also get a nice 3* or higher via Priceline around $35-40, whereas roaming and using Motel 6 or others at just a night apiece seems significantly more expensive (even after inflation) than years ago. Being able to cover a lot of ground on early trips was a good overview for later ones, though.