The new Hyundai Sonata Hybrid features an EPA-rated 40 miles per gallon on the highway, which leads its class and beats out popular models like the Ford Fusion and Nissan Altima hybrids. So how did Hyundai's engineers pull it off?

CNET recently profiled the innovative powertrain lurking in every Hyundai Sonata Hybrid. Engineers were given a task to maximize the car's fuel economy, so they started by sculpting the body in order to make it as aerodynamic as possible, which reduces drag and slightly increases mpgs.

Hybrids are at their best when the electric motor is powering the car, but many of the strategies for achieving this are patented by the South Korean automaker's top rivals. So Hyundai invented the TMED, a transmission-mounted electrical device. The TMED features the motor and clutch in one package, allowing the car to use an automatic transmission without a torque converter. The system not only lets Hyundai to get the best gas mileage on the highway in its class, but also run up to 75 miles per hour on electric power alone.

Looking for an upgrade to your own mileage? Then it might be wise to trade your vehicle in for a new one, as technology has increased significantly in recent years, leading to drastically increased mileage ratings without a significant dip in power. Those interested may want to head to New Jersey State Auto Auction, which features a wide variety of vehicles available for well below Kelley Blue Book value.