WHAT is the car of the future going to be like? Is it going to be a variation of the Toyota Prius, with its petrol-electric hybrid drivetrain? It certainly is an elegant piece of engineering. In the Prius (say ‘Pree us' and not ‘Pry us') there's a frugal 1.8-litre engine and an 82bhp electric motor on board. Either one can drive the car independantly, or both of them do at once when you want to accelerate hard.

That gives rise to all sorts of clever functions. The Prius has a smallish battery on board, and it's easily topped up either by the petrol engine or when you brake for corners or coast to red lights. The car never needs to be charged by an external source, in other words.

So while most of us simply boil off kinetic energy as we slow down, the Prius stores it up for its electric motor. When you've stopped at a red light, the there's no need to have the engine running, so you save fuel. In  start-stop rush hour traffi c the electric motor allows the car to crawl along, so you save fuel. Even if you're moving along at a smart clip, the electric motor gives the engine a helping hand so you save fuel.

The end result? Toyota says the latest Prius should average 25.6km per litre. So yes, if we want a more sustainable motoring future, the Prius provides a wonderful template. Except there are problems. You have to pay for the sophistication of a system with two engines and a tricky control system to juggle the power  between them, and at today's fuel prices it's practically impossible to recoup that initial extra outlay at the pumps.

Getting the best from the petrol-electric balancing act takes knack, too, and most of us will never see that 25.6km/L number. Some people might pay more upfront to do their bit for Mother Earth, but the Prius-type solution isn't for all of us.

How about the Chevrolet Volt? This car represents General Motors' take on the hybrid idea, but GM says it's more of an ‘extended range' electric car. It has an electric motor to drive the car, and you can charge its batteries when you get home by plugging it into the wall socket. Here's the interesting bit - if you average 64km or less per day on your daily commute, you're like 75 per cent of Americans, and GM says if that is how you use your Volt, you might never need to use petrol power at all.

It's only when you exceed 64km that the Volt's petrol engine fi res up. It never drives the car directly, but  charges the battery so the electric motor can keep going. The fi nal result is anything between 21.3km/L  or a whopping 62.5km/L. Best of all, if you can fi nd a power point to mooch off at work, half your traveling will be "free".

Like the Prius, though, the Volt will be expensive. It's those darn batteries again, plus the need to have two engines instead of one. It will be a technology for the relatively wealthy - like automatic transmissions, air-con or power steering were - before it trickles down to the mainstream as production economies kick in.

Trouble is, the wealthy are more interested in a luxury cabin and high performance, not fuel frugality. Presenting the Volt's technology in the everyman Chevy might have been a miscalculation on GM's part. Some carmakers think pure electric vehicles are the answer. Nissan, Ford and Audi are all promising zero-emissions electric cars within a decade, for example. Where does the juice to charge the cars come from? Well, a third of our national power grid is fed by hydroelectric sources, so electric cars are a decent solution for Malaysia,
environmentally speaking. But the battery technology needs to improve drastically. If you've ever winced at the
cost of replacing your laptop's battery, which you can hold in your hand, you know they are hideously  expensive. While electric motors are reliable, what happens if your electric Audi's batteries conk out?

You're looking at a fi ve fi gure sum for replacement. And the fi rst fi gure isn't going to be 1, 2 or even 3.
Mitsubishi plans to sell an electric car called the i MiEV, basically a version of the cute Mitsubishi i with its turbo engine gone and an electric motor in its place. It will travel up to 160km before you need to plug it in for the night, and it  tops out at 130km/h. It offers perhaps as much room an d practicality as a Kelisa, but my guess is that if it were sold here it would cost ten times as much as one.

Does that sound like a workable solution to you? If it's beginning to sound like we're all in trouble, there is one remaining technology that we haven't explored: diesel. Forget about that smoky stuff that belches out of trucks.

The modern diesel  is excellent for the environment, if you think CO2 emissions are important.

In a half-million-a-year market like ours, if you get 50 per cent of buyers to switch over to diesel (which is roughly what happens in Europe today), the country would consume about 70 million litres less fuel every
year, according to calculations from auto supplier Bosch.

250,000 diesels a year is doable here, and it's an instant jumpstart to any Green ambition. Toyota took 10 years to sell 1 million hybrids around the whole world, remember. The bit that excites the Chinese person in me is that diesel is the ultimate bargain. Not only is it cheaper to begin with, but it's also a denser fuel. For every 10 litres of petrol you take on, you get 7.2kg of fuel, whereas diesel's greater density means you would get around 8.5kg of fuel. Since you buy fuel by the litre and not by the kg, that makes diesel doubly good value for money.

The engine technology is pretty relevant to our palm oil producers, too. People sometimes forget that Rudolf Diesel designed the engine that took his name to run on peanut oil, and the oil industry created diesel to suit the engine later on.

As talk of biofuels ramps up, it's worth remembering that the diesel engine was always meant to run on plantderived oils, so taking a serious look at these engines to come up with a suitable fuel could give Malaysia world leadership in that area. As always, there's a clincher. You need good, clean low s ulphur diesel to run the latest, cleanest diesels, but guess where we stand on that? Our Euro 2 compliant diesel has a sulphur content of 500 parts per million (or ppm), while the current Euro IV compliant diesel cars need fuel with a tenth as much sulphur or less.

So we're stuck with the fuel of the past while everyone has moved on to the car of the future. What are we missing out on? Take the Audi A5 3.0 TDI, for instance. It's a sexy coupe that hits 100km/h as quickly as a Lotus Elise (6.1 seconds), but the V6 engine averages 16.9km per litre of diesel. If we were serious about this tech, we could have Protons  and Peroduas running on torquey, frugal diesels achieving mileage close to that of the Prius, but we don't even have the fuel for it yet.

And in case you doubt that diesel engines aren't smoky anymore, another study from Bosch found that one diesel engine running idle for 100 minutes emits as much soot as a single cigarette. And that was an older Euro 3 emissions compliant  engine. I'd rather sit in a restaurant with a modern diesel car running next to me
than eat beside a smoker. But  first we need the proper fuel for it.