Q. How will the 54.5 mpg law in 2025 affect non-hybrid cars? How likely is it that the law will do away with naturally aspirated and non-hybrid drivetrains?
A. You will certainly see more hybrids and turbocharged engines -- and electric vehicles as well -- over the next 12 years or so as automakers scramble to meet the 54.5 mpg standard set by the federal government. But you also will continue to see naturally aspirated non-hybrid vehicles for two key reasons: They cost less than the alternatives, and the auto industry continues to wring more mileage out of the internal combustion engine, as evidenced by the growing number of conventional cars rated at 40 mpg on the highway.
Another reason is that every vehicle won't have to get 54.5 mpg by 2025. That regulation could have nearly as many loopholes as the IRS code, so the internal combustion engine should survive for years to come.
It will be even more of a four-cylinder world in 2025 than it is today -- even the BMW 528i has a standard four-banger -- and there will be engines with fewer cylinders. For example, Ford says it will offer a 1.0-liter three-cylinder engine next year in one of its small cars. Most vehicles will shrink at least a little in size and probably a lot in weight from wider use of aluminum and other weight-saving materials, and they also could have less sound insulation as another way to shed pounds in the interest of fuel economy.
Although the traditional gasoline engine will survive, it probably won't run accessories such as power-steering pumps, air-conditioning compressors and water pumps that used to be driven by engine belts. Those are rapidly being replaced by electric components that operate only when necessary and don't sap power from the engine through what engineers call "parasitic losses" that reduce fuel economy.