I know the envirowackos think that cars are going to disappear at some point in the future. They won't but there are plenty of alternative fuels that will replace gasonline and diesel.

We will be buying natural gas fueled vehicles in larger numbers over the next decade (Honda already sells one), and mass produced all electric commuter cars will be a reality within 5 years.

The most promising replacement fuels compatible with existing internal combustion engines include DME and cellusolic ethanol.

Cars aren't going away, but many of them will become lighter, smaller, and much more fuel efficient.

Karlock is correct: trolleys and light rail consume a disproportionately large amount of current infrastructure spending. The peak oil thesis only matters if you think that petroleum is the only way to fuel automobiles. It's not. Petroleum has retained it's dominant market share because it is relatively abundant and (up til now) cheaper than alternatives.

The future will be every bit as auto-centric as the past 50 years. We need to improve and expand our road and bridge capacity accordingly.