Cars are complicated beasts, but there are five main approaches to making them more efficient: adjust driver behaviour, improve the engine, reduce the impact of the fuel, or the body and tyres, or the manufacturing and recycling process.
Size matters
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Smaller, lighter cars tend to be more efficient
In general, the lighter the car you buy the less CO2 it produces. Less than 1% of a traditional car's fuel is used to move the driver. The vast majority, about 87%, is lost as heat and noise in the engine, pollution controls and in transmitting the power to the wheels. Of the remaining 13% or so that actually reaches the wheels, around a third overcomes drag, a third overcomes resistance of the tyres on the road (rolling resistance), and only the final third accelerates the car. In other words, to get a unit of power at the wheels, a typical car uses seven or eight units of fuel. Therefore a saving of one unit at the wheels through decreasing drag, rolling resistance or weight, will save seven or eight units of fuel in the tank. So, for the most part, if you want to make a car more efficient, it is more important to make it light and lower drag than make its engine more efficient or improve its fuel, so smaller and lighter cars tend to be more efficient.
(Sources: Winning the Oil End Game p46 box 6. Amory B. Lovins, E. Kyle Datta, et al. Earthscan, London 2004)
How can you tell if a car is green?
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New cars are now sold with efficiency labels, just like fridges!
Answer: Look at the label. New cars are sold with banded efficiency labels, like fridges. Soon, the scheme should be made compulsory and extended to second-hand cars. And all cars are now taxed according to how much carbon dioxide and other pollutants they emit. For details of how much your car emits, see the Vehicle Certification Authority website. The crucial measurement is how much CO2 per kilometre they emit, and there is surprising variation, with cars of about the same size and class varying as much as 45%.
When a dead car is a good car
Over a car’s life, from production to destruction, most of its emissions of greenhouse gases are down to the fuel it burns, and EU legislation means that average car efficiencies are improving rapidly. So if your car is an old one, getting rid of it for a newer and if possible, a smaller one is a greener option than hanging on to your banger.
Over to you
Cars of the same size vary hugely in efficiency: if everyone switched to the most efficient car in the same class, emissions from cars would fall by 30%. New developments in fuels, engines, aerodynamics and ultra-lighting all have the potential to make cars much more efficient… and they’ll be here all the quicker if we demand them.
How well you drive and look after your car, what ever it is, has a big effect on its efficiency. Start today and you can reduce emissions, save fuel and money - everybody wins - including our planet. Read our top tips for green driving
London Congestion Charge discounts
Did you know that London Congestion Charge discounts are currently available for the greenest cars. If you have to drive into the Congestion Charge zone on a regular basis, the annual congestion charge can amount to over £2000 per year (£8 per day). Due to their low levels of regulated emissions, the greenest cars are eligible for 100% discounts under the current system. When visiting the Sexy Green Car Show look out for all the cars that are eligible.
However, from 27th October 2008, a new CO2-based London Congestion Charge will be introduced. Under the new emissions-based scheme, cars with CO2 emissions of 120 g/km or less (VED bands A and B), which are also Euro IV vehicles and registered since 01 March 2001, will receive a 100% Congestion Charge discount.
From 27th October, cars with CO2 emissions greater than 225 g/km (equivalent to the new Vehicle Excise Duty band G), as well as those registered before 01 March 2001 with engines larger than 3,000 cc, will face a London Congestion Charge of £25 per day. The majority of cars, VED bands C, D, E and those in F with emissions up to 225 g/km, as well as those registered before 01 March 2001 with engines up to and including 3,000 cc, will continue to pay exactly the same daily charge as at present (£8).
Under the new scheme, vehicles already registered for the Alternative Fuel Discount will continue to receive the discount until January 2010, unless the vehicle changed ownership. The current discounts and exemptions for Blue Badge holders and Taxis & Licensed Private Hire Vehicles will be unaffected by these proposals. Under the Congestion Charging NHS reimbursement scheme, eligible claimants are reimbursed the £8 daily charge. This scheme will continue for the £8 standard daily charge; however those drivers of band G vehicles will only be eligible for £8 reimbursement rather than £25.
MORE INFORMATION:
Visit TfLs's website for details of current London Congestion Charge discounts
