Hybrid vehicles have always offered more benefits to the zip-around-town Domino's pizza delivery boy than the long-distance highway commuter. In fact, without regernative braking at work, a hybrid vehicle at highway speeds exhibits very few efficiency advantages over a frugal MINI Cooper.
Addressing one of the problems, Honda is now touting a "heat-harnessing hybrid", claiming it can recapture energy that most conventional hybrids lose during high speed driving. Greatly simplified, the innovative approach uses exhaust heat to convert water to steam. The steam turns an electric generator that then charges the vehicle's battery pack. It's all based on an age-old principle called the "Rankine cycle." Pre-boomers may recall it's the same type of technology that was used in the Stanley Steamer a century ago.
Honda crammed all of the "heat-harnessing" plumbing into a Honda Stream prototype and captured three times as much energy as a regenerative braking system on the EPA highway cycle. While that may sound impressive, the technology still needs to come a long way and the price fall before we find steam generators in our cars. Thanks to Sylvester for the tip!