As fuel-economy challenges go, this one was unusual. To promote its new E-Class Hybrid, Mercedes-Benz raced the car up a couple of airport runways as fast as its diesel-electric powertrain could manage. Before running out of airstrip, the E300 BlueTec Hybrid hit 136mph at the first airport, and 120mph at the second, due to a rather shorter runway.
While that doesn’t sound like a recipe for great fuel figures, the twist in this story lies in the location of the two runways. The first serves the mainland’s most southern working airport, in Newquay, Cornwall. The second landing strip is in Wick, Scotland, the most northerly equivalent. The two are separated by 830 miles of our crumbling and congested British blacktop, and the car had to get from one to the other on a single tank of fuel.
Including the airport blasts, the two-day end-to-end journey was completed at an average speed of 49mph, with the dashboard indicating average consumption of 67.3mpg – sufficient to leave a quarter-tank of fuel at the end of the trip. Clearly the driver possessed a relatively light right foot, given that the official combined-cycle score for the car is 65.7mpg.
Either figure is impressive, underscoring that an already efficient diesel engine can still be helped to greater heights of economy with a little electric hybridisation.
In the E300’s case, the car’s 204bhp, 2.1-litre four-cylinder turbodiesel is supplemented by a 27bhp (20kW) electric motor. The motor has been unobtrusively squirreled away inside the housing of the car’s unique seven-speed automatic transmission, while the 0.8kWh lithium-ion battery has been stashed under the bonnet, replacing rather than joining a standard lead-acid lump.
The result is no loss of luggage capacity for the hybrid in either saloon or estate guise, while hitting CO2 figures as low as 109g/km for the four-door and 116g/km for the load-lugger.
The hybrid battery isn’t huge – it stores about a third less energy than a Prius’s bulkier NiMH pack – but it’s enough to make a noticeable difference in power, flexibility and economy.
The E300 hybrid can scuttle to 62mph in 7.5 seconds and – given a long enough runway – reach 150mph. Not bad for a very sizeable, economy-biased luxury saloon. The snag, as ever, comes at the purchase point. Prices start at £39,645 for the saloon and £41,435 for the estate, towards the upper end of E-Class menu.
I’m due to test drive the E300 Hybrid in early October. I don’t think there will be any runways involved, sadly, but I’m looking forward to the opportunity nonetheless.