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Hybrid cars

Hybrid cars are part battery-electric and part conventional cars. The underlying principle of all hybrid vehicles is the use of a temporary energy storage device (usually a battery), which enables the main engine to be operated at close to its maximum efficiency.

• How do hybrid cars work?
• How do I refuel a hybrid car?
• Are hybrid cars better for the environment?
• What are costs of owning a hybrid car?
• Where can I buy a hybrid car?

How do hybrid cars work? Return to top

Two types of hybrid drive have been developed. 'Series hybrids' use a combustion engine to generate electricity, which powers an electric motor so providing motive power. In 'parallel hybrids', the wheels can be either directly powered by the engine or from a battery-powered electric drive-train. In both types, when the engine loading is low, the excess energy is stored for later use. When more energy is required, the main engine and the energy storage device work together to deliver the required power. In this way, hybrids provide improved fuel economy and reduced emissions.

Hybrids are classed either as 'mild' or 'strong' to reflect the degree of battery power incorporated into the design, strong hybrids being able to spend more time in electric-only mode. Most hybrids operate in electric mode at low speeds, which makes them ideal for urban driving. Battery storage enables the use of regenerative braking which tops up the battery during braking, further reducing overall fuel consumption by around 20%.

The driving performance of hybrids is not unlike that of a conventional car, road handling is very similar and acceleration is broadly comparable or even slightly improved. From the outside, most hybrids look little different from other new conventional models – other than sporting a 'hybrid' badge – with their additional dashboard information, its from the driving seat you are more likely to be aware of the differences of hybrid car design. On pulling away, and at low speeds, you may also be aware of the lack of engine noise (while in electric-only mode).

How do I refuel a hybrid car? Return to top

As all hybrid cars currently on the UK market use conventional petrol, fuel is dispensed from fuel pumps in exactly the same way as for conventional cars. Indeed, the great advantage of petrol- (and diesel-) fuelled hybrid cars is that they require no change in fuel and so use the existing UK fuelling infrastructure.

As the driving range and fuel economy of hybrids is better than their conventional counterparts there are no restrictions on the applications for which they can be used. With no technical barriers to their use, hybrid vehicles therefore possess great potential to become the new standard automotive technology of the next decade.

Are hybrid cars better for the environment? Return to top

All regulated emissions are significantly reduced for a petrol-hybrid passenger car as compared to a conventional petrol vehicle. These include typical reductions in carbon monoxide, hydrocarbons and NOx of 70% to 90%.

Most petrol-hybrids reduce lifecycle greenhouse gas emissions by at least 25% compared to an equivalent petrol car. For example, the new Toyota Prius achieves CO2 emissions of just 89g/km – with lifecycle NOx and particulate emissions over a quarter less than those for an average conventional petrol car of the same size. NOx and particulate emissions are also negligible at point of use, but marginally increased during the manufacturing process – however this tends to be done away from urban areas.

Unlike other green cars, the future of hybrids is not threatened by the improving fuel and emissions performance of conventional cars. This is because a hybridised engine will always outperform its non-hybrid equivalent. The second reason, and the most telling, is that all conventional engines may have to be hybridised if they are to conform to future emission standards. In other words, the future conventional and hybrid cars may be one and the same.

What are costs of owning a hybrid car? Return to top

Some ownership costs for hybrid cars are higher than for their petrol and diesel equivalents, due principally to the higher purchase price. Typically, for new car, the additional purchase price is in the range of £1000 – £2000 (on a £14,000-£16,000 model). Purchase prices are expected to fall with time.

Most running costs are less for hybrids than conventional vehicles, the higher capital costs are offset by lower fuel costs due to the high fuel economy of the vehicles themselves. As is the case with carbon emissions, hybrids typically use 15%-30% less fuel per mile.

Other changes in ownership costs include 'road tax' (Vehicle Excise Duty) – most hybrids are charged less than their conventional equivalents due to their lower emissions of CO2. In the UK, it may be the case that hybrids will have reduced depreciation for the next few years (i.e. they keep their value longer) as the demand for hybrids is likely to grow.

For drivers in and around London, another major running cost to consider is the Congestion Charge – all hybrids currently receive a 100% discount (although owners of hybrids need to register with Transport for London and pay an annual £10 fee). With a £8 payable daily charge, this could provide a potential annual saving of up to £2000.

STOP PRESS: London Mayor, Boris Johnson, has proposed to replace the Congestion Charge's 'Alternative Fuel Discount' with a 'Greener Vehicle Discount'. If accepted, the Greener Vehicle Discount (GFD) would provide a 100% discount for all cars (hybrid or otherwise) that emit 100 gCO2/km or less and meet the Euro V standard for air quality. See news article for details.

Where can I buy a hybrid car? Return to top

At present, several hybrid models are available to buy in the UK, from a range of manufacturers. One of the first and still the most popular is Toyota's Prius, now in its third generation. Toyota is also releasing the new Auris hybrid in 2010, which uses the same 'Hybrid Synergy Drive' technology as the Prius, and the manufacturer is on record that it intends to hybridize its entire model range.

Honda currently offers the Civic, Insight and most recently, the CR-Z as hybrid models in the UK. A number of hybrids are also available from Lexus (part of the Toyota group), including the RX450h SUV and the GS450h executive saloon. Other manufacturers are sure to follow suit within the next few years following the popularity of already released hybrids.

The next stage of technological development of hybrids will be plug-in hybrid vehicles. The first of these to become commercially available in the UK will be a Plug-In Prius, although some companies will already convert existing hybrids into plug-ins (at a cost). Toyota's plug-in hybrid Prius will essentially be the same as the existing Prius with a slightly larger capacity battery and a mains charging plug; and takes the hybrid Prius one step closer to being a battery electric car.