Honda's Hybrid is not much greener than a normal car. But tomorrow's eco-cars are, says Steve Connor, Science Editor

There is a little game you can play when driving the Honda Civic Hybrid, The Independent's current long-term test car. It not only saves you money, it helps to save the planet. You could call it "Max MPG" because the aim of the game is to get maximum miles per gallon from your driving.

Dashboard dials informing you of speed or engine revolutions per minute can easily have the effect of encouraging a driver to burn up fuel. The nice thing about the Civic is that some of its dials are at least designed to do the opposite of this. They help you to drive in a manner that is less damaging to the environment.

The end result is that you use as little petrol as possible. The more points you win in the game of Max MPG, the more money you save and the less carbon dioxide you end up pumping into the atmosphere.

As a hybrid, the Civic has two modes of propulsion - an internal-combustion engine that runs on petrol and an electric motor powered by a rechargeable battery. The electric motor takes some of the load off the petrol engine when accelerating or climbing hills, thereby saving fuel. Although this drains the electric motor's battery, it is replenished once more when the car goes downhill or decelerates during "regenerative" braking.

Driving becomes a balancing act between taking energy from the battery and putting it back again - a process helpfully displayed by a fluctuating dial on the left side of the revs counter. On long motorway hills you physically see the power being drained from the battery, only to be recharged once again on the downhill side of the journey.

But the real fun is to see how your driving actions influence the mpg gauge to the left of the speedometer. This is real-time display of what's actually happening each second of your journey. Pumping the accelerator causes the mpg to fall rapidly. A steady 60mph on the flat gives a reading of about 50 or 60mpg.

However, the long-term mpg performance is calculated over greater distances and is shown as an accumulative improvement (or fall) in a reading next to the mileage. During the week or so I had my test Civic I was able to boost the mpg reading from a miserable 36 to a fairly respectable 43.

This is well short of the manufacturer's claim of 54.3mpg in urban driving and 65.7mpg in "extra-urban" driving. Perhaps I was still not driving the car in an optimum way - although I don't see how anyone could have driven it less aggressively - or perhaps Honda is taking a more Panglossian view of its baby's green credentials.

The real issue, of course, is whether hybrids are all they are cracked up to be in terms of being better for the environment. In ditching his official Vauxhall Omega for a hybrid Lexus, the Conservative leader, David Cameron, evidently thinks so. But a hybrid car that does 43mpg is not that much better for the environment than a conventional car that does 38mpg - which my own Rover 216 manages on my usual commuter run.

One problem with hybrids is that they need a large and expensive nickel metal hydride battery, which takes energy to produce. It also has to be disposed of safely at the end of its life. Anyone touting the benefits of hybrid cars has to take into account the energy costs of production and disposal of the extra parts that these engines need.

Nevertheless, first-generation hybrids such as the Honda Civic and Toyota Prius are the start of what could turn into a much more interesting revolution in automotive technology. No doubt performance and energy efficiency of existing designs can be improved.

But the next generation of "plug-in" hybrids, which are recharged at night from off-peak mains electricity, could be far better. The aim is to decrease the size of the petrol engine and improve the performance of the electric half of the hybrid technology. Scientists at the University of California, Davis, have built a plug-in hybrid prototype that can travel 60 miles on electricity alone with engines that are less than half the size of standard motors.

The next stage in the hybrid evolution would be to adapt the internal-combustion engine to take a mixture of petrol and biofuel - an alcohol made from fermenting crops and which is therefore not made from fossil fuel.

Some experts believe that running on a mixture of 15 per cent petrol and 85 per cent biofuel, future hybrid engines could travel 500 miles on one gallon. As only 15 per cent of this gallon is fossil carbon, it would be like travelling more than half way from London to New York on one gallon of petrol.

That would really make a difference in the game of Max MPG.

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