This is the answer.
Citroen SM.
You’re in luck! They’re making those again! Report back after you picked one up.
I had a '63 Bus. Not a Transporter, but the inside had been built out for camping (bed, closet, drawers, wardrobe, ice box, cooker) long before that was a thing. I drove the hell out of it, based in San Diego, but lots of trips up North, out to the desert, and down to Baja.
It never failed me. It also never passed another vehicle. Like … not ever 
But rot was taking out the floors and the seam that had so reliably held the roof in place.
I didn’t have the $ or the time or the experience to fix it up, so … let it go to a surfer. I had it from about '84 to about '88.
It’s really the one vehicle that I miss. I hope it’s still out there and looking pristine.
1957 Chevrolet Corvette
From 1967-71 Ford made a 4-door version of the T-Bird. My father had it as a company car for a couple of years. He never let me drive it, but it was a good ride, and he got it up to 106 mph and still accelerating once when he was passing a driver who didn’t want to be passed. I’ll take one of those in memory of him.
I assume this fantasy gift also comes with replacement AC compressors, since the ones on the T-Bird seemed to go out on my father’s every 90 days.
When I was much younger I made a list of 10 cars I would like to have, Most are unobtainable, but I recall some of them:
1970 Plymouth 'Cuda (340 4-speed)
1975 Jensen-Healey
1969-'72 TR-6
1969 AMX
1966 Corvair Corsa
1961-'70 Jaguar XKE
1971 Fiat 850 Spyder
1971-'73 Ford Mustang
Yeah, well if due to nature you had to have a substitute, that is a bloody good substitute.
Damn it…you stole my car (bus)…
But yes!
When I was a kid the wife half of a couple my parents knew had her legs crippled by polio. Her husband bought a Checker Marathon so she could stow her folded-up wheel chair behind the driver’s seat where the jump seats would have been in the taxi model. That baby lasted forever.
Just an AC Cobra 427 for me, thanks. I’m not that competitive.
Somebody in the vicinity owned one that I saw a couple times tooling along US-60. It was blue but without the stripes. Last time I saw it I was going a bit faster in the lane to the right so when I got alongside I tapped the horn twice and gave a thumbs up. The woman passenger returned it with a huge smile.
Isn’t that the car* driven by Michael Dudikoff in the syndicated tv series Cobra?
Slightly disappointed not to see any Alfa Romeos on the list. Many beautiful cars, and I’d pick a 1967 Alfa Romeo 33 Stradale.
I’ve heard these referred to as the “poor man’s BMW”, because they had similar power and size to the contemporary BMW 2002, and both had independent suspension.
I was also leaning towards something Japanese, I was thinking maybe a '76 Toyota Celica.
Or, as Superintendent Chalmers once said: “I used to think a car was just a way of getting from point A to point B, and on weekends to point C. But that was the old me! That man died the moment I laid my eyes on the 1979 Honda Accord” (except a few years older to meet the criteria of the thread). Actually looking at Wikipedia the Accord just barely meets the thread’s 50 year old criteria – they were first sold here in 1976 as a '77 model. I assume we’re going by actual age and not model year, so an early build '77 Accord that was built in 1976 would count.
Although I do have to say the aforementioned BMW 2002 would be pretty tempting, too.
I was thinking about something like that, but have you seen the price of gas lately? I assume we’re responsible for buying gas in this scenario.
Well now! That is an amazing automobile and one I’d love to have a chance to drive. But you think you could use that as your primary transportation for a whole year? I suspect you’re tougher than I am.
Also, I imagine it’s a complete bear to get parts for. Even if Czarcasm is footing the bill, I expect any part that was needed would need to be made from scratch. 18 built.
That’s why I’ve tried to avoid museum pieces in these threads.
Also, what’s the minimum number of factory built (or sold in kit form) examples for homologation as factory built in this thread? More than one?
Shoot the moon, go for the 1970 Cuda AAR: 340-6bbl, side pipes, 2700 produced. Pity no Shaker hood on the AARs.
This is my choice. I’ve spent most of my life being disappointed in every car I’ve owned since because they were never as perfect as that '71 2002 that I bought used from my sister’s boyfriend.
Although it was fun, powerful, roomy, and reliable the feature that I miss the most is 360 degree visibility, nothing but glass all around. Modern cars may be safer with the crash steel in the doors, but I’d rather take the risks that low window sills entail. Damn I miss that car.
The most fun car I’ve ever owned was a '57 Triumph TR3. I was a fool to ever sell that car.
The most fun car I ever rode in was a Porsche 356C ('56 or '57?)
But given the current state of my knees and especially my back, I’d have to pick the most comfortable car I ever rode in, a '66 Caddy.
Yeah, boring, I know.
If it was a '56 or '57, it would have been a 356 or 356A. The 356C wasn’t introduced until MY 1964.
Well, in my defense, it was over 50 years ago. 
It was probably a 356A then.