Petrol

Cars running on unleaded petrol have fallen out of favour in the UK fleet market due to the increasing focus on CO2 for taxation, resulting in diesel cars being the fleet favourite.

However, recently there have been a number of advances in petrol engine technology that are challenging diesel's dominance, with a number of petrol cars actually reaching similar levels of fuel economy to diesels. This helps some petrol cars gain a cost advantage over diesels that often have a significant price premium.

However, towards the end of 2009, the difference in pump price of petrol and diesels has narrowed, meaning diesel still tends to hold its cost advantage over petrol for fleet cars.

Diesel

Diesel has been the fleet champion for many years now due to high efficiency common-rail direct injection systems providing low CO2 emissions and excellent fuel economy.

Whole life cost analysis usually reveals some of the cheapest car running costs. Diesels are much cleaner now than they have been historically, due to particulate traps and ultra low sulphur fuel, but petrol cars will typically produce lower exhaust emissions.

Diesels are still, in the main, the most cost effective no-compromise fuel type for company cars.

Traditional fuels - with cutting edge technology.

The focus on saving fuel and reducing CO2 - and hence costs - is yielding a new breed of low emission, high fuel efficiency car.

Advances in engine technology are enabling smaller engines to produce increased power, hence replacing old larger units while improving fuel efficiency and emission profiles. This is being achieved through a combination of enhanced engine technologies, regenerative braking, engine downsizing, reduced vehicle weight, improved vehicle aerodynamics and optimised transmission systems.

Many view the combination of these approaches to be the short-term environmental solution, with most car manufacturers rushing environmentallyfocused products onto the market. These include Efficient Dynamics (BMW), TDIe (Audi), BlueMotion (Volkswagen), DRIVe (Volvo), ECOnetic (Ford), EcoFLEX (Vauxhall) and Ecomotive (Seat).

These are low risk options which minimise fuel consumption and hence reduce fuel costs and CO2 based on taxation costs.