1991 Mitsubishi 3000GT VR4, twin turbos, all wheel drive, all wheel steering, electronic controlled suspension, active exhaust, active aero - lots of do-dads for it's time. When it's running right, it's a blast to drive! But lots of things to go wrong. When you need parts, they are frequently either no longer made or very expensive. I've got way more money wrapped up in mine than it will ever be worth, so I'll probably have it forever.
I too have owned Renaults--13 4CVs (over the years) to be exact...but having bought out the local dealer of related parts when they ceased operations in 1974, I don't lack for parts...except for my '56 convertible. Less than 6000 convertibles were built out of 1.1 million 4CVs produced, and in 1956, 12 or 13 were imported to the US--as US-specific models, thus different from the French Metropolitan cars in several aspects--and mechanically different from the 1955 and earlier convertibles. And mine was in a tornado, further adding to its restoration challenges.
My other "challenge" is a 1949 Fiat Topolino woody station wagon--real structural wood, not trim. From the cowl back, the body is unique to the wagon--and they made about 400 that year. I know of one other in the US.
I would choose a fully sorted Citroen SM with fuel injection...and a nearby specialist to keep it that way...and enough cubic dollars to support him. I have had some of these cars and I love the way they hit their stride beyond 80 mph and make pot-holes and speed bumps some else's problem.
I was just looking at an auction for some Mitjets. Seems like they would be fun track day toys but ball joints from a mid 90s Renault might be a bit hard to source anywhere around here if one was to break.
My 91 Allante
I love the car, but it is loaded with 20 year old electronic gadgets and Allante-only parts
Want list: Jensen Interceptor iii