I agree with the suggestion that there's nothing wrong with trying to contact the seller by telephone, and to do so courteously.

Don't be too disappointed if it doesn't work out for you to pick up the car this Saturday, either. It would be great if it were to work out that way, but to presume that the seller's schedule for a particular day will be compatible with your schedule would be, well, presumptuous.

Note also that the seller's feedback - though overwhelmingly positive - is almost entirely from sellers. So don't be surprised if they don't have a smooth "eBay seller thing" going - including checking and responding to e-mails frequently.

Don't even waste your energy getting worked up about eBay feedback at this point. There is plenty of time for that later when the dust has settled.

Enormous cool factor for the car, too! I hope it works out great for you.