Opinions vary wildly on whether you're better off buying a car that runs on diesel or petrol.

Most small cars have petrol engines, while larger vehicles often come with diesel engines. Diesel engines have long held a bad reputation for noise and pollution, but they have come a long way in recent years. Diesels are usually the best option financially if you tend to make a lot of long journeys, diesels are not as economic if you mainly use a car to drive around town or do short trips.

So what are the basic facts about petrol and diesel, and which is best for you?

Fuel Economy

Diesel tends to be less expensive to buy at the pump than petrol, and diesel engines tend to be more efficient and so require less refilling. In fact they are 30-40 percent more fuel efficient than petrol engines.This means not only are you saving money on fuel but you save the time spent filling up more frequently at the fuel pump. However, it is important to bear in mind that diesel vehicles are usually more expensive to buy in the first place.

Experts suggest that if you drive fewer than 15000kms in a year that you are better off buying a car that runs on petrol.

Noise

Years ago, you could always tell when a diesel car was coming along by the clatter the engine made, but modern technology has all but resolved that. More precise fuel injection systems have put a stop to the noise to the point that if you were stood next to a car with the engine idling, you'd find it near impossible to determine if it was a petrol or diesel by the engine noise alone.

And over the next few years, we can expect the difference to become even less noticeable, meaning that the issue of noise when choosing a diesel has now all but been eradicated, so long as you're buying a newer model.

Pollution

Debate continues to rage over how environmentally-friendly diesels are. In Paris the mayor has tried to ban them from the streets altogether, while in the UK some local authorities, notably in London, have begun imposing higher charges for parking permits on diesel-drivers due to the perceived impact of diesel emissions on health.

But several leading car manufacturers have questioned the theory. They argue that because diesel engines are more efficient with fuel, they actually reduce CO2 emissions and thus air pollution.

Nevertheless, the chemicals released by diesel engines are a major concern to environmental campaigners right now, While diesel technology is becoming more advanced - with particulate filters having been introduced, this is something to consider.

Servicing

Generally, when it comes to routine maintenance and servicing, there is not much difference between diesel and petrol cars. But when there are major engine problems, it is often the diesel that proves more expensive to fix. This is especially an issue with the aforementioned particulate filters which can cost several thousand dollars to replace. Not something you want to go through twice!

Power

Diesel engines are generally more powerful than petrol engines from lower revs. If you want that extra torque for some pulling power - perhaps if you often have a caravan or trailer behind your car - then a diesel is going to be a more attractive option.

Resales

Petrol cars are usually less expensive to buy, but a diesel will tend to retain more of its value, so if you plan to sell it on in a few years then you might want to look at a diesel instead.

Whether are best buying a car that runs on diesel or petrol will essentially depend on your needs, budget, and how many kms you expect to do every year.

CONCLUSION

Unfortunately there is no clear winner as both engine types have their pros and cons and are better for different purposes. Although diesel vehicles have copped a bad name through stories in the media concerning the impact that their particulates have on our health, most of those cases are to do with older diesel engines. The more modern diesel engines are certainly worth considering especially in regards to the benefit of their fuel economy and performance off-road.