While General Motors and Ford have made progress in retooling their gasoline engines to make them more fuel-efficient, Chrysler has lagged. Now Chrysler hopes to catch up with the MultiAir technology, which it claims will increase fuel economy by 25 percent.
In a conventional engine, a camshaft opens and closes the valves that bring air into the engine. These valves all make the same movement all the time, even at low engine speeds, when less air is required. The MultiAir system is different because it electronically determines the most efficient way to open and close the valves, depending on road conditions and necessary power, allowing the car to run more efficiently at all speeds.
Here's how it works: A small solenoid, a mechanical device that can act like a switch, opens and closes the valves. This solenoid adjusts the cycle of valves opening and closing so that the engine takes in the best amount of air for the load it's handling at any given moment. Opening the valves for a short period of time at low loads is less work for the engine, increasing its efficiency. And because the system can open the valves longer when more power is needed, it can extract more energy out of the engine.