Oldest car that can be used as a reliable daily driver?

Anything that uses a 12 volt electrical system, about mid 50's for most makes.

I've been driving an aircooled 1200cc 1969 Karmann Ghia for the last 4 years, almost every day.

It just takes a little extra maintenance.
That, and if you want spirited driving, it's a lot less forgiving.

Even in the 60s freeways had speed limits of 55 mph most commonly though my dude

43 ford truck

you are really tempting fate to dd anything with 4 wheel manual drum brakes

just my two cents

I remember the first time I locked up all 4 wheels and slid into an intersection. Good times.

Any age will do as long as it has cruise control and decent power for climbing 2000ft of elevation. 35 miles of interstate wouldn't be fun without cruise.

Yep. My great grandma drove her '67 Impala daily til she passed a few years ago.

Power brakes and steering start to be common options in the 50s

What's wrong with the earlier 6v systems that used generators?