Michelin prototype on Geneva-launched eco Citroën
The Citroën Hybrid Air has enjoyed its world premiere at this year’s Geneva Motor Show, and the technology is expected to be in production by 2016. Based on a petrol engine and hydraulic components (engine and pump) but no battery, the French car maker states that Hybrid Air technology combines ground-breaking performance with maximum accessibility. Citroën claims the Hybrid Air demonstrator can achieve 2.9 litres of fuel per 100 kilometres, with carbon dioxide emissions capped at 68 grammes per kilometre; in comparison the Citroën C3, at the same power, uses 4.5 litres of fuel for 100 kilometres and emits 104 grammes of carbon dioxide per kilometre.
The Hybrid Air shown at Geneva is fitted with prototype Michelin tyres. Like the Bridgestone concept tyres shown at the show these are ‘tall and narrow’ tyres, in this instance size 165/50 R18. Michelin says the tyres on the Hybrid Air prototype help reduce carbon dioxide emissions by 4.3 grammes per kilometre and fuel consumption by 0.18 litres per 100 kilometres.
The choice of a narrow tyre with a large diameter makes it possible to improve performance simultaneously in different areas. The vehicle’s energy efficiency is enhanced thanks to the tyres’ lower rolling resistance and better aerodynamics, while at the same time aquaplaning resistance is also improved due to the more pronounced “ship bow” effect for narrow tyres with a wide diameter. The bigger diameter also enhances comfort by more effectively absorbing irregularities in the road surface. In addition, the tyres’ narrower, longer contact patch reduces noise. Michelin also states that it has put “a lot of work” into reducing tyre mass, achieving a reduction of 1.7 kilogramme per tyre, or 6.8 kilogrammes for the whole vehicle. This last optimization allows the new
Although no firm plans to release the ‘tall and narrow’ tyres have been discussed, Michelin says the new technologies shown in the concept tyre could “progressively be integrated into series-produced Michelin tyres in the coming years.”