2017 BMW 740e xDrive Sedan
Base price: $89,100
As tested: $100,595
Type: AWD four-door sedan
Engine: 2-liter turbocharged four-cylinder and electric motor
Mileage: 64 mpg combined (electric), x27 mpg combined (gasoline)
BMW is plugging into the electrified future of automobiles by offering a plug-in variant across its product line. The 740e full-size sedan benefits from the same lightweight carbon core construction and impressive list of technology features as the redesigned luxury flagship, but it has a 2.0-liter gasoline engine along with an electric motor powered by a lithium ion battery pack.
Plug-in hybrids differ from traditional hybrids such as the Toyota Prius, which charges its batteries mainly from regenerative braking. The main source of propulsion comes from the gas engine. Plug-in hybrids can be plugged into a standard 110-volt wall outlet or a 240-volt Level 2 charging station to boost electric power and have more gasoline-free driving. In the case of the 740e, that amounts to around 13 miles.
Thirteen miles may not sound like much at first, but there are various scenarios to take advantage of the plug-in hybrid model. Lower speed driving around town can be achieved with electric power only in MAX eDrive mode, so if your commute falls within the range, you’ll be making fewer trips to the gas station.
The car can drive at highway speeds purely on electric power, but the battery depletes faster, as would be expected. Switching to Battery Control mode, the engine will recharge the battery while driving so that once you get off the highway, which is where gas engines operate at their most efficient, the electric-only miles kick in around town, which is where hybrids are most efficient. In default Auto eDrive mode, the vehicle automatically cycles between using gasoline and battery power. Additionally, regenerative braking captures energy from slowing the car and converts it to electricity. For the most part, the predictions of available electric mileage were reasonably accurate; when plugging in, it tended to finish charging sooner than it initially displayed.
A week of mostly city driving yielded 31.9 mpg actual. That is impressive for a luxury car of this size. Its gas-only sibling 740i xDrive is rated at 19 mpg city, 28 mpg highway. There are no compromises in the performance department, as the two versions have equal acceleration numbers. Since the electric motor is incorporated into an eight-speed transmission, the driving experience feels mostly conventional; it’s extra quiet when running off battery-only power, and regenerative braking slows the car with less pedal effort.
A plug-in hybrid works well for people who might do a lot of gas-free shorter and/or lower speed trips. But you need a place to plug it in.
The techie appeal of the 740e’s electric drive component — switching between the different modes to try and optimize mileage — is really pretty neat. As cars seem to be evolving to desensitize drivers, it’s about the most engaging thing you can drive short of having a manual transmission.