Green motoring myths

According to the car industry group the Society of Motor Manufacturers and Traders (SMMT), one of the biggest challenges facing the promotion of green motoring is overcoming a large number of misconceptions held by the public towards green technology.

Given the huge amount of publicity surrounding this area I was at first slightly sceptical of this, but when I brought it up in the pub recently it turns out the SMMT was spot on – worryingly so.

Erroneous beliefs stated as fact ranged from the notion that biofuel is made mainly from the excrement of cows, to the (cough and spit your pint everywhere in disbelief) idea that electric cars cannot be driven in the rain for fear of electrocution. You really could not make it up. So here is our attempt to set the record straight, because we would hate for any of you to choke to death while enjoying your favourite tipple.

Hybrids are complicated to drive

Honda recently conducted a survey among 1,200 British drivers asking about their attitude to the environment and awareness of alternative fuelled vehicles. Worryingly for Honda – who was trying to launch its Civic hybrid at the time – 51% of those questioned did not know what a hybrid was, and many of the 49% who did assumed specialist knowledge was required to operate one.

So in case there is still any lingering doubt, let’s be clear – a hybrid is exactly the same to drive as any ‘normal’ car. That is except at low speeds in town when you have to keep swerving to avoid pedestrians who step out because they don’t hear you coming.

Hybrid cars must be recharged at night

Err, no. As the name suggests, a hybrid is a cross between a normal internal combustion engine car and an electric one, meaning it has an engine and a battery-driven electric motor for propulsion.

Hybrid cars utilise something known as regenerative braking, which basically means part of the energy that would otherwise be lost when braking or coasting, is recaptured and stored in the battery for later use.

Some plug-in hybrids can be recharged from the mains to boost their battery reserves but all models can replenish their batteries independently too.

Biofuel produces far lower CO2 emissions than petrol

This is perceived to be true because biofuel is hailed as a formidable weapon in the fight to cut carbon dioxide emissions. In actual fact, when biofuel is burnt in a car’s engine it produces slightly higher levels of CO2 than unleaded petrol, which is why it can be confusing comparing the g/km emission figure for a petrol and flex-fuel car. The great advantage of biofuel as a green alternative occurs long before it finds its way into a fuel tank – it happens when growing as a crop such as wheat or sugar cane.

Because it is a plant, it is continually absorbing CO2 from the atmosphere, so when it is finally harvested, refined and burnt as a fuel the CO2 it produces can be off-set against the CO2 it originally absorbed – known as the well-to-wheel principle. As a rough guide, a flex-fuel car running on biofuel produces about 70% less CO2 than petrol once the well-to-wheel principle is taken into account.

The faster you travel the cleaner your engine becomes

I suppose this myth has come about because it is widely recognised that a car’s engine is at its most polluting and dirty while still cold and barely moving, i.e. queuing first thing in the morning. People therefore assume that the opposite – warmed up and 100mph – must translate as the optimum for engine efficiency. As part of lengthy studies commissioned to illustrate the relationship between congestion and emissions, figures show that in both petrol and diesel engines CO2 emissions gradually reduce as a car increases speed to around 60mph (around five times less CO2 emitted compared to standstill).

However once passed 60mph, as the engine begins to work harder, this trend is reversed and emissions begin to rise. Continue past 80mph and CO2 levels rise dramatically, continuing to do so the faster the car travels.

Grants are available to help convert your car to a greener fuel

Sadly not. A few years ago the Government ran something called the Powershift scheme which helped drivers pay to have their vehicles converted to run on LPG. Unfortunately the scheme ended in March 2005 and nothing similar has been proposed since. The only green financial incentives on offer currently (apart from the price of LPG) are a reduction in road tax and possible exemption from the London congestion charge.

For the time being at least, a green choice is largely down to your conscience. Although, electric cars do currently receive a £5,000 subsidy.

A 4x4 cannot be green (and is therefore pure evil)

The reason 4x4s tend to produce high levels of CO2 is simply down to physics – they are heavier, so require larger engines, so produce high levels of emissions. Having said that, a number of modern diesel 4x4s don’t actually produce any more CO2 than a typical family estate car, so 4x4 prejudice is often founded on nothing more than ignorance.

Most economical cars in each class

Diesel cars can run purely on chip fat

For years farmers have run their vehicles on homemade forms of biodiesel, and it is indeed true that you can pore a litre of used cooking oil from your local chippie into some older diesel cars and they will run quite happily (although you may find lots of hungry dogs chasing you down the road as the smell of greasy chips wafts from your exhaust).

For modern diesel engines pure vegetable oil is simply too thick to get through the fuel pump and injectors. However, when blended with diesel in the right quantity, it can work well, with no discernable difference in performance.

Many diesel cars can run on a 5% blend of vegetable oil but more than this and you may invalidate your manufacturer’s warranty, so check first.

Petrol cars can run on cheap booze

Similar to the chip fat myth above, this has its origins in truth, but has become somewhat contorted. Most petrol engines will run on a 5% bioethanol (alcohol) blend without modification, but much more than this and the engine could be seriously damaged.

Ethanol was recognised early on by carmakers such as Henry Ford as an important fuel of the future. However, it has taken until this decade, in light of global warming, for many countries to take it seriously - and the result is E85, the brand name given to bioethanol, which can be used to power flex-fuel cars.

Hasn’t hydrogen saved the day?

Thanks largely to the way it has been reported by the media, many people seem to be under the impression that the green power dilemma has been cracked and that hydrogen is somehow the answer to halting global warming.

Interestingly, the one fact everyone excitedly repeats is that the only emission from burning hydrogen is water, so we must be saved! Unfortunately, while hydrogen does offer exciting energy prospects for the future, we are still years away from seeing hydrogen powered cars in the showrooms.

In the meantime the biggest headache for scientists is how to extract and store hydrogen so it can be made available as a fuel, without the need to first use large amounts of fossil-fuelled electricity.

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