DOSSIER I Green Fleet Management
The hybrid empire is spreading Hybridisation is no longer a technology of the future. It is about to spread across the automotive world like wild fire, affecting almost every segment. Is this a revolution?
e careful not to fall into the trap - some so-called eco cars have a very limited level of hybridisation. However appealing the hybrid solution looks on paper, it doesn’t always turn out to be so convincing in practice. To get the benefit of real practical advantage, the first thing to remember is that only full hybrid cars really deliver on their promises. These models are characterised by their ability to travel - even if temporarily - under the power of electrical energy alone. They move silently, with no vibration, and use no fuel at all when sat in a traffic jam. What a change that makes! Without going into the complex technical details about architecture or level of hybridisation, there are three different approaches in hybrid technology: eco-hybridisation, “passion” hybridisation and practical hybridisation. Eco-hybridisation The legendary Toyota Prius is the best example of the category of hybrids designed to set records for consumption. The combustion engine is big enough, but not too big, to deliver a decent level of performance when needed (1.8 litre petrol, 88 hp engine), and the electric element (the engine and battery) is ideally calibrated to reduce the consumption of fuel, but without putting too much of a strain
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on the wallet. The advantage of this configuration is that the cost is more or less equivalent to that of a comparable diesel sedan; the engine is perfectly suited to small journeys and trips around town; and polluting, noxious emissions are minimised, with none of the other constraints typical of an “anticipative” driving style. The down side, on the other hand, is that the driving experience is still slightly below par in key areas compared to equivalent conventional models, and the level of consumption is very much linked to the style of driving. “Passion” hybrids For the majority of widely-available, premium hybrid models, the intention is clearly not to offer the lowest consumption possible. Rather, the aim is to retain a level of performance identical to that of more powerful combustion engines, while demonstrating lower emission levels in hybrid mode. The inclusion of an electric motor thus enables an appreciable accumulation of power when required, while a modest, more restrained combustion engine is used in cruise mode. As specialists in large capacity cars, the German manufacturers will be making extensive use of this solution in the future. For example, the new flagship model at Mercedes, the Class S, includes no fewer than three different hybrid solutions in its catalogue. The diesel hybrid version makes do with a “small” four cylinder 2.2 litre engine backed up with a 250 Nm torque electric motor. Hence it offers performance levels more or less equivalent to those of the version V6 3.0 litre diesel, while reducing the standardised consumption from 5.6 litres/100 km in the V6 diesel to 4.4 litres/100 km for the hybrid variant. Effectively you get the benefit of a driving experience equivalent to that of an engine with a larger capacity, but the real bonuses of the configuration are largely academic and financial. Here again, the reduction in consumption during use is very much related to the driving style adopted. Furthermore, the possibility of driving in purely electric mode turns out to be somewhat limited (only over a short distance and/or only at low speed).
Published on Jan 24, 2014