Designed for Power
It was ready to go, to hug the asphalt with its tires and tackle every bend with a roar of pleasure. But it held back, because the first job that morning was to drive the children to school. All of its drives start off silently and electric. After all, it is well mannered, and doesn’t come barging through every door.
The electric motor and the combustion engine work together very closely. The electric motor with 70 kW (95 hp) is housed between the V6 engine and the eight-speed Tiptronic S automatic transmission. This degree of proximity promotes symbiotic behavior: the electric motor supports the combustion engine in nearly all driving situations. For maximum acceleration, the two assemblies join forces to generate a system output of 306 kW (416 hp). At more leisurely speeds and at high rpm levels in general, the combustion engine works a little harder than it needs to, in this way charging the battery via the electric motor. At the same time, the combustion engine is used in an efficient range of rpm and engine load. The only thing the driver notices about their joint efforts is the presence of propulsive force, not where it comes from. “One of our most important goals was that the driver wouldn’t notice the transitions between different modes of operation,” Jörg Kerner, the director of powertrain development at
Upon entering the village, we gracefully glide by the gas station to our left. The car consumes only about 3.4 liters per 100 kilometers according to the official NEDC. This figure can be even lower in day-to-day driving if the battery is recharged regularly. Short trips can be made on electric power alone. The car is charged with environmentally friendly electricity at home in the garage by means of the
An automobile that performs like a sports car but emits less CO2 than a compact without an electric drive—this idea was the brainchild of a handful of engineers at the Weissach Development Center in 2009. “A purely electric car was never what we were after,” says Uwe Michael. As an engineer in charge of electrical and electronics development, he was one of the initiators. “We wanted a solution that was suitable for actual driving,” he adds. The conventional hybrid drive that had already been developed lowers fuel consumption significantly. But its effect is limited by the fact that its battery can be charged only when driving by means of brake energy conversion and the combustion engine (load point shifting).
In order to set new fuel consumption records for everyday driving, a car needs to drive faster and farther on electric power. In other words, the battery must be rechargeable externally and have more capacity. Also, the electric motor needs to be more powerful. To resolve these issues, the
The big day came in May 2010: the first plug-in hybrid
Right before the freeway on-ramp, the
The car changes character at the press of a button. The engineers have come up with four driving programs. E-power mode is always used to start up the car. When the battery is (almost) empty, the car switches to Hybrid mode, in which the combustion engine takes over the main role. At speeds of less than 154 km/h, the engine is switched off and disengaged as soon as the accelerator pedal is released. The car then “coasts,” minimizing drag and also saving fuel in the process. In Sport mode the combustion engine always runs, and the battery maintains sufficient power to make the next spurt with maximum output. In E-charge mode, the battery can be charged on the go at any time if desired—for example, on the freeway to generate sufficient electric power to drive around town later on.
“We had intense discussions about the operating strategy,” says powertrain director Kerner. It would have been easily possible to include even more driving programs. The 918 Spyder, for example, has an additional Race mode and a Hot Lap mode in which the high-performance battery is briefly pushed to its limits. “But this car has a different character,” notes Kerner. And the drive system of the 918 Spyder is also physically different because it has two electric motors. One operates on the rear axle between the V8 engine and the transmission, and the second sends an additional 95 kW (129 hp) to the front axle. When the peak torque of 1,280 Nm is summoned, the driving dynamics benefit significantly from transferring power to both axles.
Whether we’re talking about the 918 Spyder or the
With the destination in sight, the multifunction display announces that the battery is full again. Switch to E-power mode. The
By Johannes Winterhagen
Engine: Supercharged V6 engine
Displacement: 2,995 cc
Power: 245 kW (333 hp)
Maximum torque: 440 Nm at 3,000–5,250 rpm
Power electric motor: 70 kW (95 hp)
Maximum torque electric motor: 310 Nm < 1,700 rpm
Total power: 306 kW (416 hp)
Total maximum torque: 590 Nm at 1,250–4,000 rpm
0–100 km/h: 5.9 sec.
Top track speed: 243 km/h (151 mph)
CO2 emissions (combined): 79 g/km
Fuel consumption (combined): 3,4 l/100 km
Electric power consumption (combined): 20,8 kWh/100 km
Efficiency class: A+
Milestones in the development of cars with combustion engines and electric motors
With the Semper Vivus (“always alive”), designer Ferdinand
The second generation of the
About a year before the start of production, a hybrid super sports-car prototype of the 918 Spyder set the fastest lap time ever for a street-legal car on the Nürburgring—but one year later Marc Lieb is 17 seconds faster, posting a time of 6:57 minutes in a 918 Spyder production car. The powertrain is designed for racing: the high-rpm V8 sports engine powers the rear axle together with an electric motor. A second electric motor powers the front axle. This type of all-wheel drive transmits up to 1,280 Nm of torque to the wheels.