It depends on what kind of life you want to live and how small of a world you want to live in. Being car light gives you the best of both worlds. Bike everywhere where it is practical, drive when it makes more sense. My girlfriend drives everywhere, I bike everywhere, sometimes we drive together. The total mileage on that car is well below 15k a year and costs about $500 a year to maintain. If we want to take off for a trip to the next city over, we can and it doesn't have to be on the bus or train's schedule. This kind of flexibility sometimes makes life more enjoyable with more variety.

Buying more car than you can afford or driving excessively for no good reason is something else entirely. I believe it's called "stupidity" and has nothing to do with simple/non-simple living.