"Dumb car" is kind of relative. Computer engine controls have been around since the mid 1970's. And while the first ones were not very good, they have become pretty darned reliable over the intervening years. And as someone who has owned cars and other heavy equipment with mechanical points and down draft and up draft carburetors, you won't ever see me willingly own a car with any of that anymore.
If you really want to minimize the electronics as much as possible, look at 1990's to no later than 2010 models.
Though to be fair, much of the problems with cars are caused by the accessories like power windows, door locks, air conditioning, and power seats. Those are far more problematic than the basic car itself.