[lesuorac]

Naw, the most economic solution is to make bigger bumpers and let cars push each other forward.

Think about a hose. If you have it at a certain flow and then increase the flow the water doesn't go out faster because it wants it. It flows faster because it's being pushed.

Same thing with cars, as more cars get onto the highway you want them to go at a higher speed so that the throughput matches the on ramp. We just need to cut down the number of 4 lane highways so that we have space to put exit ramps on both sides of a 2 lane highway but the increased speed will make up for it.

[stetrain]

Yes, we should just make couplings so that a long string of cars can be attached together. The trailing cars could all follow the lead car. If you add some guide rails to the road you don't even need a fancy autonomous steering system. Swap the rubber tires for steel wheels on the guide rails and you reduce friction losses and eliminate flat tires. A centralized dispatch and signaling system could keep the system free flowing and enable high capacities.