Hybrids and diesel both add significantly to the purchase price of the vehicle. Economics may, in fact, be the biggest obstacle to mass acceptance for both technologies, according to a report on Hybridcars.com. The average added cost of a full hybrid on a small car is $3,332, according to a Department of Energy report. Diesel engines are already more costly to manufacture than comparable gasoline engines because they need higher-pressure fuel injection systems. Meeting future pollution limits that make diesel as clean as gasoline will require additional, costlier pollution-control systems. The average added cost for a diesel engine on a small car is $1,750, the Department of Energy report said.Compared to gasoline engines of the same size, diesel engines today get 35 percent better fuel economy and produce 25 percent more power (torque). In meeting future tighter pollution limits, diesel engines will have their fuel economy advantage fall to between 30 percent and 33 percent.As an indication of how significant the pollution problem still is for current diesel engines consider that the diesel Jetta is rated 4 on the EPA’s Air Pollution Scale (1 to 10 with 10 lowest pollution) whereas the gasoline Jetta is rated 8. On the same scale, Prius earns a 10 and Escape Hybrid earns an 8. The stricter pollution standards for diesel engines do not fully take effect until 2007.Availability of diesel fuel is a concern for many drivers. Only about 33 percent of neighborhood service stations carry diesel.Diesel suffers from an image problem, according to the report. Owners of gasoline vehicles generally still believe that diesels are noisy, smelly and underpowered relative to gasoline vehicles. In large part, this is due to unfamiliarity with modern diesel technology. Compared with 1988 diesel technology, modern diesels have 100 percent more power, 60 percent less noise, 90 percent lower emissions, and 30 percent less fuel consumption. Modern diesels are not noisier than gasoline engines, do not produce a diesel odor, and accelerate as well as comparable gasoline vehicles. This suggests that many of the negative perceptions about diesels held by car buyers could be overcome with greater exposure to modern diesel vehicles.The producers of the hybrids that have so far been sold in the U.S. have tended to compromise power and performance in their pursuit of high fuel economy and low pollution. Most American new-vehicle buyers care more about power and performance than fuel economy and pollution, so to become mainstream hybrids need to offer more, the report says. The Ford Escape Hybrid, the mild pickup hybrids from GM (Chevrolet Silverado and GMC Sierra) the new Accord Hybrid, and the announced SUV hybrids from Toyota (Lexus RX400h and Highlander) all move in the direction of offering power and performance.A USA Today reporter compared a Volkswagen Jetta TDI diesel and a Toyota Prius hybrid on long drives. His verdict? “Prius is comfortable, a festival of technology and unquestionably cleaner-burning than the VW can be today with only high-sulfur diesel fuel available. But the real-world mileage of pleasant-driving Jetta was better than that of Prius, and diesel fuel typically was 16 percent to 20 percent cheaper than unleaded gas. Jetta lived up to its one-tank billing. Prius did not.”Popular Mechanics compared many diesel models with hybrids. The writers concluded “that the real gains in fuel economy were to be found in driving habits, not necessarily in either drivetrain technology. The hybrids do better in urban, stop-and-go driving while the diesels come into their own over the long haul, especially when towing or climbing grades. But diesel fuel is smelly and can be hard to find. Hybrids may have repair and reliability problems down the road.”How big could the hybrid and diesel markets become in the U.S. in five years? Hybrids and diesels could each represent 5 percent to 10 percent of new light-vehicle sales in the U.S. by 2010 and 10 percent to 15 percent each in 2015, according to the Hybridcars.com report. Hybrids will probably achieve higher shares sooner than diesels. Makers of hybrids are already starting to offer the broader mix of hybrid technologies and vehicle capabilities that will be needed to attract more mainstream customers. Makers of diesels still face significant issues in reducing pollution from the engines before they will be permitted in large numbers in most of the U.S.