August 2010: Car models are changing rapidly and if you're thinking of buying a new car, now is a good time to consider which fuel would be best for your particular type of use.

Why choose diesel?

Diesel is cheaper than petrol ? see below, typical price listing in August 2010

Compared with the cheapest petrol 92 Unleaded, diesel is 40 cents cheaper per litre!

Diesel cars are often capable of providing better outright consumption and thus diesel is a better choice for larger or heavier cars that come with 4WD (4-wheel drive) technology.

Also if you are doing 10,000km a year you should be looking at a diesel car to make substantial savings.

The downside is that parts for diesel cars are usually more expensive, and you need to service the car more frequently.

Why choose petrol?

Diesel cars cost more. Also you need to pay more in road tax.

Currently, a diesel car attracts a road tax and a special tax, which is four times the annual road tax. From July 1, 2008, the special tax structure for Euro IV-compliant private diesel passenger cars will be changed to an absolute-dollar tax based on the engine capacity of the car, at a rate of $1.25 per cubic centimetre of engine capacity, subject to a minimum tax of $1,250. As a result, the special tax for Euro IV diesel cars could be reduced to about 2.7 times the normal road tax.

A petrol car is often a wiser choice for those who are intending to buy a small sedan or a medium-sized car.

Petrol is one of the most efficient kinds of fuel available.

Petrol does not produce excessive toxic emissions nor particulates.

This is usually achieved by synchronizing and controlling petrol engine drivetrains with the help of computer chips. These computer chips are often assisted by low-friction materials that are light as well.

Modern petrol cars will be able to make use of the minimum of fuel in existence and reducing emissions considerably while delivering reliable performance.

Then, there is the variable valve timing technology. Such a technology is capable of altering engine displacement depending on the way of driving performed by the driver. By using this technology, petrol car engines will be capable of shutting down some cylinders while they are not quite in use and thus save the fuel consumption.

Fortunately, there are indeed some ways to save the fuel no matter if it is diesel or petrol.

First, buy a car with automatic transmission which usually consume less fuel compared with a similar car with manual transmission. An automatic uses a torque converter instead of clutch to manage the link between the transmission and the engine. Unfortunately, the car engine may waste fuel due to torque converter.

This is one reason manufacturers such as BMW, VW or Fiat are introducing new automated manual transmission that comes without a clutch. This is another technique of saving fuel and reducing emissions.

An engine's output is rated in horsepower and torque. Torque is pulling power, the twisting force created in an engine by rotating parts, while horsepower is the measurement of how fast torque is being used.

If you're not towing or carrying heavy load, torque shouldn't be a deciding factor when choosing a car.