My perfect car…hmmm…let me think about that…
Well, first of all, it would have to be designed for very easy servicing.
It would also have to be big enough to accomodate 5 passengers in comfort, with abundant legroom and headroom, and a floor without a “step-down”-- but not so long that it is a pain to do parallel parking.
Most likely a wheelbase of ~113 inches, with an overall length of ~194 inches, and a width of ~70 inches would provide that combination of generous interior room, coupled with a relatively compact exterior.
It would have to have power that is more than just adequate, coupled with class-leading fuel economy.
Most likely, an engine of ~4.5-5 liters would provide that good balance between power and economy.
It would have to have a logically laid-out instument panel, equipped with easy-to-read gauges and no idiot lights.
And, of course, it would need oversized disc brakes.
Oh my God!
I just described a 1964 Studebaker Lark Cruiser sedan!
Yup, all you would need to do is to adapt the engine to fuel injection and computerized engine controls, fit it to a modern 5 or 6-speed automatic transmission, and make it compliant with modern safety regs, and you would have a sedan that would still look contemporary, and would rival the less-expensive Mercedes sedans in terms of performance, albeit for…many thousands of $$ less.