Oh, and I know what you mean about what if motorway vehicles could just travel a bit faster. Move everybody faster and there will be fewer cars on the road at any time. I mean, that's how it works when you build more roads, right? Building roads = less traffic. That's why we have so many more roads now than 40 years ago and why road traffic levels are so fantastically reduced now compared to the 1960s/70s. More roads => less traffic, faster speeds => less traffic. Obvious and inevitable, right?
(The phrase you're looking for is "supply that stimulates demand", btw)
Safety?, pah!
All we have to do is make cars stronger, to withstand crashes better, they'll be heavier and that will make them so much more fuel efficient and require less energy to make them, too, won't it? We could have stronger and better crash barriers (somehow that will reduce the risk of crashes happening
). Sure the barriers will need more material and be more energy intensive to manufacture, but hey, it's worth it for that 8 minutes saving per hour, right?