[JadeNB]

> It is easy to build a city where you can reach everything you need within 15 minutes by car.

I think getting to places by car is often not the hardest part. Instead, the hard part (at least from a user's perspective!) is storing all the cars for all the inhabitants of the city, both at their origin and their destination. This creates ballooning space requirements, including duplication of space (much residential parking will remain largely unused during the day, and much business parking will remain largely unused at night). Then, even after devoting as much space to cars as US cities do, one winds up unable to plan simply to drive to one's destination, but having also to devote significant planning to parking.