I did one once, in a rented Avis Pontiac Bonneville... Washington, DC to Seattle, Washington... September 13-15, 2001.
Three work colleagues and I were stuck in Washington during 9/11 and aftermath. We'd flown into DCA on the 9th or 10th on ATA and when DCA was shut down indefinitely, so was our route home. On the Wednesday night of that terrible week I rang Avis and inexplicably lucked into an incredible one-way deal, if I'd come up to BWI to collect the car... which I did, on a Thursday morning train. The airport was as close to an armed camp as I ever hope to see in this country, but Avis was terrific.
I drove back down to DC and collected my friends. We left Lafayette Park on Thursday afternoon around 300pm and got to the Fauntleroy ferry dock in West Seattle at 900am Saturday. Around 2800 miles in 45 hours flat, and we squeezed in a couple of restaurant meals too -- Friday lunch at an Applebee's in North Platte, Nebraska, and Friday dinner at some sort of seafood house north of Salt Lake City. I-90, I-80, and I-84 were rivers of Fords and Chevys and Pontiacs with bar codes on their rear windows... about every fifth car was full of grounded businesspeople driving home.
The tab was about $225 plus ten tanks of gas. By Thursday or Friday the car rental firms had cottoned to the opportunity and were starting to charge insane, holdup rates for one-way rentals, but we were, as I said, lucky to get in early.