Have you tried Dwolla?
Dwolla? Really? Dwolla? An unknown internet site that takes forever and a century to clear funds, isn't a regulated or recognized financial institution? People will accept a personal check LONG before they buy off a "now, I'm going to enter a few numbers into this web site and you'll see your money in your bank account in about 3 days. Oh, and I'll need your account's electronic transfer code, and I'll be driving off with your car as soon as you sign that title..."
I too have bought several cars with cash, and I know what I'm talking about. You clearly do not. (p.s, other guy: instead of cash, try cashier's check. most people are willing to accept that if you negotiate it beforehand).
Actually I use Dwolla as my preferred method of payment for my business. I have had 4 clients since I started using Dwolla two months ago start paying me through Dwolla.
It's not unknown Internet site, and is actually partnered with a number of banks. It doesn't take 3 days for the transaction to show up in your account, that happens immediately. It also doesn't take 3 days to pull it into your bank account. That happens in one banking day, since it's merely a "checking" front end tied to your banking account.
And furthermore you dolt, people would accept a Dwolla payment LONG before they accept some fucking retarded bitcoins that they have to A. Make a Dwolla account to get USD out of anyway becuase they have to go to B. fucking Mt. Gox or some other stupid exchange, and THEN, trade their bitcoins for USD, pull it BACK into their Dwolla account, and THEN AGAIN wait for it to go into their bank account.
So let's see, in your idiotic scenario where cash is such a motherfucking hassle and for whatever reason you were too stupid to originally consider a personal check since that's apparently a better option for this hypothetical seller, then what would the seller rather do? Create a Dwolla account, get verified, and basically have the money deposited directly into his back account, or go through a bunch of goddamn asinine intermediary steps with bitcoin markets to get his USD out of bitcoin?
You my friend, have just been made a fool of.