the system works best at low speeds and in stop-and-go traffic.

Ratings for highway fuel economy increase about 10 percent to 36 m.p.g., but the city ratings increase from 22 m.p.g. for the base four-cylinder model to 41 m.p.g. for the hybrid. In the real world, gas mileage of the hybrid varies greatly depending on how the car is driven.

Reasonably driven, the test Fusion approached 40 m.p.g. with little traffic and few red lights. But when pushed, fuel economy suffered quickly and fell to the low 30s. On a 70-mile test loop with mostly 45-60 m.p.h. travel, the Fusion Hybrid returned about 37 m.p.g.

Driving the hybrid is also slightly different than driving the standard model. As long as the plan isn't to race the car stoplight to stoplight, the average driver won't notice the electric motor under the hood.

Tooling through a parking lot at the mall, the Fusion Hybrid is happy to lope along on battery