Smaller engines are more thirsty
21 March 2007
It's wrong to do what the DfT is doin and automatically equate less powerful engines with frugality, argues The Insider
I take absolutely no comfort in winning arguments about fuel economy and CO2 emissions, unless it's the Government I'm arguing with. There's usually no-one available to argue with of course, but that just increases the win rate.
The Department for Transport is now trying engage us as a country in a campaign to Act on CO2, using billboards and a website (www.dft.gov.uk/ActOnCO2) depicting a cartoon engine belching smoke. Weighty advice like "pump up your tyres" and "why not consider a more fuel efficient engine?" is offered to prick us into driving greener.
I've no problem with that. Bit of education, no extra taxes or paperwork - suits me fine. However, my years of experience have taught me that often seemingly obvious advice has very different outcomes when applied to fleets, particularly when that advice is based on the lying 'official combined' consumption figures.
Key to the DfT's advice is that we should think about choosing a smaller car. Now, I once met a bloke who drove 100,000 miles a year (absolutely true this) working as a recruiter for a security firm. That security firm had done a bit of homework and figured out from somewhere like the Vehicle Certification Agency that the most efficient five-door car was the Suzuki Wagon R. Yep, that tiny, 1.3-litre shopping box designed to incorporate big-haired Japanese septuagenarians.
Except in the hands of this harassed recruiter (who lived in the wilds of North Wales), the Suzuki only managed around 30mpg.
“It's an ironic fule of thumb that the most efficient car is often the more powerful.”
The trouble with most petrol superminis is that the gearing is designed to exploit the minimal power, and not necessarily the economy. So at the hands of the permanently tardy fleet driver, the frugal little city worker becomes as thirsty as a petrol BMW on motorway journeys.
It's an ironic rule of thumb that the most efficient car is often the more powerful. The Suzuki driver put his foot down, found nothing, and put his foot down some more. The BMW driver is satisfied with the little foot-flexing he has to apply (okay, maybe not all BMW drivers).
I know a company boss who's also a keen racer, a hobby that led to him becoming increasing annoyed at the power flat spots in the small fleet of petrol Seat Leons he'd just acquired. He took them to a tuner, who re-programmed the ECU to get rid of them. Result was more power, but also significantly better economy as the drivers now didn't have to mash the pedal to drive through the flat spots. The tuner told him these flat spots were there because the car companies know exactly what speed and gear the official economy tests are conducted in, so programme the engines to achieve better results. Good for our taxable CO2 figures I suppose, but bad for economy in the real world. Just one bit of useful economy information you'll never find on a Government billboard.
The Insider is a fleet manager with years of invaluable experience