Automakers remain divided on whether diesel or hybrid cars are the best way to improve fuel efficiency, and the split is often drawn along cultural lines, according to the New York Times newspaper on August 4. All the major manufacturers are developing cleaner diesel engines, hybrids, and hydrogen fuel cells. But companies are pushing harder on different technologies to get a leg up in meeting regulations that are becoming tougher around the world, and their views were represented in comments made at a recent management conference. Toyota and Honda developed hybrid-electric vehicles, in part because they save the most gasoline in the sort of stop-and-start driving that is common in the clogged traffic of densely populated Japan. In a hybrid like the Toyota Prius, an electric motor takes over for the gas engine at low speeds and stops; energy is also preserved that is usually lost in braking. But automakers in Europe are skeptical about how profitable hybrids can be and prefer diesel-powered vehicles because they offer car owners an alternative to high taxes on gasoline. Environmental advocates remain cautious about diesels. Compared with conventional gasoline cars, they offer lower emissions of the kind that contribute to global warming but lag behind in emissions of smog-forming pollutants – though filtration technology is improving. New air-quality rules that will be in effect in the United States by the end of the decade will require diesel and gasoline engines to meet the same emission levels. Tom LaSorda, chief operating officer of the Chrysler division of DaimlerChrysler, which includes Mercedes, said the company was still researching hybrids and had not settled on an offering beyond a small-volume version of its Ram pickup truck to be introduced in the fourth quarter. "The other one we're really pushing on, and we think will work, is the diesel," he said. "We're starting to see a lot of positive market response from our dealers and customers out there that would like to drive clean diesels in the United States." Later this year, Chrysler will start selling a diesel version of the Jeep Liberty sport/utility vehicle, the first diesel other than a pickup to be offered by one of Detroit's Big Three automakers in a couple of decades.