I average 18mph (burst of up to 30mph) on a7 mile ride and I have never been unable to hear approaching cars from behind. Do I trust my ears alone? No. But I've never been surprised by Prius, Volt, Tesla Roadster, or any other hybrid or electric vehicles. In biking events or on bike paths I can even hear approaching bicycles from behind (bike chain, wind, and tire noise). So I'm surprised that wind noise overpowers car noises for you.
It's been interesting to see all the comments about this! Obviously it's struck a nerve...and danger aside, I'm happy to see a number of people less than thrilled about the idea of noisier hybrids and EVs. There has to be a better solution.
The 1865 act required all road locomotives, which included automobiles, to travel at a maximum of 4 mph (6 km/h) in the country and 2 mph (3 km/h) in towns and have a crew of three travel, one of whom should carry a red flag walking 60 yards (55 m) ahead of each vehicle.
Backup audible warning is already implemented on most trucks, commercial vehicles, municipal vehicles, etc. That is not a bad idea; the driver has limited view, and risk is higher. But that is totally different than always on noise generators.
Festo's BionicKangaroo combines pneumatic and electrical drive technology, plus very precise controls and condition monitoring. Like a real kangaroo, the BionicKangaroo robot harvests the kinetic energy of each takeoff and immediately uses it to power the next jump.
Design News and Digi-Key presents: Creating & Testing Your First RTOS Application Using MQX, a crash course that will look at defining a project, selecting a target processor, blocking code, defining tasks, completing code, and debugging.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.