About the only technical advantage the NB4L has over the first generation ADL Enviro400H was that all the anciliaries like power steering pumps and what have you are electric, so you can stop the engine and run on pure battery power, only kicking the engine back in when needed.  Obviously this stops the engine at bus stops and in stationary traffic, saving fuel, it’s what modern cars do and is a Good Thing.  More conservative designs based on conventional diesels (like the original Enviro400H) couldn’t do this as they ran anciliaries mechanically from the engine, requiring the engine to be running to be able to steer, for instance.  They’ve now seemingly overcome this judging by a very bullish press release yesterday:

The company already has 600 hybrids operating in the UK, in many cases achieving fuel and CO2 reductions of 60% compared to previous diesel equivalents. Their latest technology will introduce stop-start hybrids, enabling zero emissions as vehicles pull away from bus stops. ADL expects this to reduce fuel consumption and emissions by another 8-10%.

8-10% is about what I’d expect the environmental margin of the NB4L over the Enviro400H to be at best, so we’re possibly talking very little difference here other than the ADL product is cheaper, carries more people and, being built in large numbers, is more readily available.  Indeed, ADL are already churning ‘em out:

All 150 stop-start ADL hybrid-electric vehicles will be delivered between now and the summer of 2013. Operators receiving them are Metroline (19), National Express Dundee (9), National Express Wolverhampton (12), Stagecoach Manchester (40), Stagecoach Sheffield (19), London United (29), Go-Ahead London (18) and FirstGroup (4).

Assuming the First ones aren’t for London, that’s 66 straight off the bat over the next six months, probably before the NB4L is really going to be in series production given the need to remove about 5% of it if the design capacity is to be reached.

Is Boris’s New Bus now Old Hat?  I think we should ask more questions.

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