Good question

In my diligent search through the web to find articles of interest about energy, fuel saving measures, and efficiency I happened upon an article from the Technology Review published by MIT entitled Why Not a 40-MPG SUV. The substance of the article was that, despite the remonstrances of (particularly) the U.S. automobile industry, the technology is available now to bring relatively large and comfortable SUV's that achieve a fuel efficiency of 40 miles per gallon.



This was of particular interest to me since I drive a relatively large and comfortable SUV, the Land Rover LR3 HSE that has been the subject of many of the articles I've posted. Now, none of the technologies described in the article can be retrofitted to my vehicle, but they could be brought to market by the time I have to replace the LR3.



Some of the options reflect methods I've already incorporated into my regimen, such as engines that turn off and restart at stoplights, etc. The development is a starter /generator that has sufficient power to start the engine without noticeable lag when a driver steps on the gas after a stop. The current state of the art requires a 42 volt electrical system and is a way out into the future. As detailed previously, I simulate this at relatively long stoplights and on long downhill cruises and make up for the lack of instant starting ability with anticipation.



Some of the developments detailed are already beginning to appear, one example is the continuously variable transmission. Clearly, the ability to run in a narrow band of r.p.m.s regardless of vehicle speed will result in more efficient operation - this is one reason why modern locomotives are hybrid diesel electric propulsion systems wherein the diesel engine runs at a constant r.p.m. to operate electric motors that provide the motive force.



Some are much farther out, including engines that operate without camshafts to operate the valves. Electronic controllers can do a much more efficient job of opening and closing the valves, but are quite hard on them using current technology. Camshafts are more gentle, engineers are investigating various damping systems to reduce the electronically controlled valves impact on valve seats.



There are several more methods under development detailed in the article. Contemplating the individual financial savings as gasoline creeps seemingly inexorably toward $4/gallon and considering the impact on our need to import oil, it's high time we got down to it.