The tunnel vent is lined up with the shoulder area of the occupant. On larger passengers, the shoulder engages the vent and keeps it from venting so the gas stays inside the airbag. On smaller passengers, the effect is just the opposite: Because the occupant's shoulder is below the vent, the gas vents out of the airbag.The driver's airbag uses a reconfigured curve-shaped tether system that pulls in the lower section to create a pocket that help to lessen the impact of the airbag on the driver's chest and ribs in frontal crashes. Deploying at the same time is a driver's knee airbag. Top fuel economy, driver assist technologyThe Fusion and Fusion Hybrid boast leading fuel economy and numerous technologies that help enhance the driving experience, reduce stress and assist the driver. Fusion brings the broadest selection of fuel-efficient powertrains in the midsize car segment. Consumers have the choice of a pair of EcoBoost four-cylinder engines, a normally aspirated four-cylinder engine, an automatic start stop system to shut off the engine at stationary idle, front-wheel drive and all-wheel drive applications, and a choice between automatic and manually shifted six-speed transmissions. Maneuvering parking lots and traveling open roadways becomes less stressful with Fusion's available sensor-based BLIS ® (Blind Spot Information System) with cross-traffic alert. The system uses radar to identify and alert the driver if a vehicle is detected in the vehicle's blind spot. Cross-traffic alert provides audible and visual alerts if traffic is detected approaching from the sides, such as when backing out of a parking space. Available Active Park Assist makes parallel parking virtually stress-free. With the press of a button, the system detects an available parallel parking space and automatically steers the vehicle into the space. Drivers control only the gas and brake pedals and transmission gear position.