One element Geoff doesn't cover in the comparison, which I think will slow the take-up, is that the lifecycle of a phone (<2 years) versus the lifecycle of a ca

One element Geoff doesn't cover in the comparison, which I think will slow the take-up, is that the lifecycle of a phone (<2 years) versus the lifecycle of a car (4-5 years?). And those (from memory, please correct with data) are median averages. For every person still toting an iPhone3 I imagine there are scores still driving a 1993 Camry. Smartphones exploded in use over the timeframe described, because the technology improved rapidly AND consumers upgraded 2-3 times so could choose the newest and best. Even if cars had similar tech trajectories, the market is moving more slowly. Of course, electric cars have a secondary market that's much stronger than used phones, which will work against my numbers.