Thanks E-P for your quick discussion on Knock Sensors. I always assumed that they kept you very close to the peak....fringe knocking for maximum performance and economy. Never heard a tech discussion that included the "leading edge" stuff like throttle plate changes. My 1994 Lumina must have been a little slower, you could get a good rattle when cracking the throttle from an idle but then be unable to get another for a long time. Octane 85 Fuel: My last "totally mechanical" ignition advance car was a 1978 Zephyr. Borderline ping at sea level (Iowa) on Octane 87, not ping at all on 85 in Colorado (9,000 feet, Summit county) on our annual Ski Trip Once found some 83 octane near Aspen, still could not get a ping out of it. Ya just gotta be careful to run it down and refill with something better as you leave the mountains, that stuff would begin pinging dangerously in Nebraska!! Hopefully the knock sensors have eliminated much of that danger.

Roger, reduce the gas tank from 11 gallons to 5 gallons to save 43lbs? Really? So those commuting any distance would need to purchase gas every day? We can always choose to leave the tank half empty when just putting around the neighborhood!

Better yet, a 50 cent increase each year for 10 years. Balance the budget, allow huge tax cuts for middle class citizens...........and actually do something about co2 emissions!

Are these guys (Researchers Splitter and Szybista) a little bit late to the parade? They used ethanol to allow them to use an 11.8 to one compression....careful combustion chamber design and direct injection (Mazda Sky-Activ) already allows compression ratios as high as 14.5 to one without any ethanol. There is little..if any...benefit to raising compression higher than that, even diesel efficiency peaks out near there....they may run compression a little higher for starting purposes, not for efficiency. So, you would just be back to about a 10.5 percent mileage decrease using the 30 percent ethanol due to the reduced energy content. Once again, ethanol would mostly serve to reduce range and mileage of your vehicle, while increasing operating costs - assuming ethanol paid its share of road tax.

Hmmmm...public records show Gevo's total contract to be worth 639,000 dollars....The navy is paying $26 per gallon per the contract. The big player, with the biggest contracts for biofuel purchases and study projects here was Tyson Foods....who has given 1.9 million in political donations......nope, Unless Obama is a Republican he did not get it.... Be careful of what Rush tells you. We should support "startup" research and funding on butanol.....ethanol would be a huge penalty in aircraft both due to its corrosiveness and due to poor energy density.

Well said, Thomas.... good mileage comes from looking ahead and paying attention to traffic lights. Many drivers power toward red lights, then stop abruptly.... just as the light turns green and they restart again. Double waste, both fuel and gas.... and some safety loss also, reducing speed ahead greatly reduces the chances of hitting the stopped vehicles in front of you in poor conditions. Most of the lights that I drive through have predictable patterns.... no need to race toward a light that you cannot possible make. The most ridiculous waste that I can think of: My city put in synchronized traffic lights on two one way streets FIFTY years ago. The lights are synchronized at a speed slightly below the limit, as traffic is often heavy in this area. The waste: MANY drivers accelerate briskly toward each light, brake hard, nearly stop, gun it again as it turns green FOR THE ENTIRE 30 BLOCK DISTANCE. After 50 years they have paid so little attention to their driving that they have not noticed yet!! I suspect many hypermilers make better time than most drivers, while getting much better mileage. Those that pay attention generally win!!

The claimed efficiency increase comes from the lack of heat loss to the non-existent cylinder head. To conceptualize this: Take a picture of an OPOC engine and draw in a wall between the two pistons. Yes, so that both pistons compress against their own head. Note the tremendous increase in surface to volume area of the combustion chamber.... a thermodynamic loss that is huge. Now, remove the wall between the cylinders and recalculate.... Basic physics/thermodynamics predicts a considerable increase in efficiency....only time will tell how much....45% claims seem high but even 20 percent would be huge. Heck, the 40 mpg Corolla/Civic... etc would now be at 50 mpg...... that would make $5 gas easy on the pocket. No valves, they do have to be two strokes, but my outboards are in daily use and run for 10 years easily so.... maybe no worries there??

OOps, meant to type Cruze with 42 mpg under the new system, would have been 45 just a couple of years ago! Like others though, I would look forward to a Civic Diesel!

EPA numbers have been revised downwards three times. -- you cannot compare the numbers from different years. The first numbers were unrealistically high, and difficult to obtain even with the (then) 55 mph limit. The first downward revision in the early 80's was about 22 percent. Since that time they were revised downward again in 2008, about 10 percent, then lowered another 10 percent this year. So a 57 mpg Rabbit back then would now be nearer a 40 mpg estimate. Our 2007 Corolla (stick) was 41 hwy then, I think it is now 38..... It gets a lot of 40 mpg hwy tanks with a skilled driver. I suspect the Cruze with a 45 mpg number on the new system will often return nearly 50 for skilled drivers.. amazing, whaddya think. I have been driving small cars for 40 years, 30 mpg used to be good!! Goracle, you have revealed your prejudices and ability to twist the facts, without having revealed any evidence to support your claim.