Mercedes-Benz will turn the S-Class limousine into its first plug-in hybrid and plans to spread it around the world, including Australia.
The S500 Hybrid is being pitched as a substitute for the S500 twin-turbo V8 for power, torque, performance and speed, but delivers fuel economy of just 2.8 litres/100km.
Details of the plug-in hybrid were revealed in England this week by Mercedes-Benz hybrid powertrain technical project manager, Dr Uwe Keller, but the biggest shock is the car’s limited electric range.
The E500 Hybrid mates a twin-turbo, 3.0-litre V6 petrol motor with an 85kW electric motor to punch through to 100km/h in just 5.2 seconds, with a 250km/h top speed.
However, in an age when even Audi’s A3 e-tron plug-in hybrid delivers 50km of pure electric driving, the S500 Hybrid manages only 33km.
Oddly, the car will need to increase its electric range to 50km within two years so that it can meet China’s minimum range rules for plug-in hybrids.
Dr Uwe Keller, Mercedes-Benz’s technical project manager for powertrain hybrids explained that the Magna Steyr-built battery pack had room for developments, which were coming thick and fast.
“We don’t just want an electric car, but the best real hybrid. Its role is to deliver a car that is everything, not just an electric car.
“We will have to fit a larger battery for the Chinese market in two years, approximately, because of their laws so we will look at larger capacity in the same power packet and space,” he explained.
While the car ekes out strong fuel economy and emissions of just 65 grams, it doesn’t want for performance.
Its biturbo engine has already been seen in the CLS 400 and delivers 245kW of power and 480Nm of torque, which is added to thanks to the additional 340Nm of torque from the electric motor.
It doesn’t use the much-vaunted nine-speed Mercedes-Benz automatic, preferring to stick with sitting the electric motor inside the bell housing for the traditional seven-speed transmission.
“It uses the seven-speed transmission. The Newtons we get are constant from the electric motor until 2500rpm, so it is not really necessary to have nine speeds,” Dr Keller said.
“Even then, we could get more than 800Nm out of the system but we limited it for consumption and efficiency.”
He also hinted strongly that the S-Class was just the first recipient of the powertrain, which will find its way into most large, expensive Benz models above the E-Class.
“We have hybrid in each rear-wheel drive models and now we have started with plug-in hybrids with the S-Class.
“We could imagine that we would put in 500-badged models above E-Class. We could work on that.”
The S500 Hybrid is capable of running as a pure electric car, as a conventional hybrid, with the petrol motor charging the battery or with the car running on the petrol motor alone while it saves the electric power for a dense inner city further along a route.
Part of the problem in the S500 Hybrid’s fuel range is that the car is just so heavy. The 8.7 kW/hbattery pack alone adds 100kg, while the rest of the hybrid hardware adds another 100kg, so the limo adds up to more than 2.1 tonnes. And it also retains the 72-litre fuel tank.
“But if you run it as a hybrid, it will deliver 149 grams normally, but then you take into account the electric range and that drops the number down,” Dr Keller insisted.
“If you use it as a full hybrid, and not a plug-in hybrid, it would use 6.4 litres/100km and that is a 50-grams reduction from the V8, so that drops to 149 grams from 199.
“It’s all about downsizing and lowering emissions without losing any performance, so while it’s coming with a V6, we have to calculate everything about it against the V8.
“It will have similar price range to the V8 around the world, but the exact figure depends on the market.”
Meanwhile, one of the next steps on the way to perfect electric drive and plug-in hybrid vehicles is wireless charging. Daimler and BMW have now agreed on jointly developing and implementing one common technology.
Mercedes-Benz says that wireless charging of the battery will make the handling of electric drive and plug-in hybrid vehicles even easier. The company says it will commence fleet testing of this ‘unplugged’ technology with the S500 plug-in hybrid soon.