Public transport can emit less pollution than private vehicles, per person transported, and can be the most sustainable form of motorised travel. However sometimes car use is essential and in some cases environmentally preferable. If you do choose to use a private vehicle for a given journey it is important to reduce its environmental impact to the minimum. One important factor is your choice of fuel.

Cleaner fuels range from the small but useful emissions savings enabled by using super unleaded petrol and super diesel to potentially larger emissions savings from biodiesel and biopetrol (bioethanol), LPG and Natural Gas (NG).

Super unleaded petrol is generally 97 or 98 RON as opposed to 95 RON for standard petrol. Most of the major manufacturers offer a super unleaded alternative (such as Shell Optimax and BP Ultimate). Branded super fuels contain detergents which clean your engine as you drive helping to maintain lower emissions and fuel consumption throughout the vehicles life. The higher RON rating helps the fuel to burn more cleanly in advanced engines, providing more power and torque whilst also reducing emissions. Super diesel shares these benefits whilst lowering emissions of NOx and PM (what does this mean?). Super fuels do cost more to buy but this is offset (potentially completely) by the reduced fuel consumption. Their performance advantage and emissions reductions have been independently verified. If you want to use a petrol or diesel vehicle there really is no excuse for not using super fuels.

Biodiesel is a relatively common site on UK forecourts but its availability on Merseyside has historically been poor. However, thanks to the Government's decision to introduce a Renewable Transport Fuels Obligation (RTFO) both biodiesel and bioethanol will be commonplace in the not to distance future. The RTFO  will be introduced in April 2008 and by 2011 5% by volume of UK road fuel sales must be from renewable sources. The Government will review the 5% limit after 2011 with a view to increasing the percentage mix of biofuel if possible. Using biofuels helps to reduce emissions. The actual reduction in CO2 emissions varies widely depending upon the feedstock and the production method. Some methods result in more CO2 being released than using standard fuel whilst others are CO2 negative (they remove more CO2 than they emit). It is anticipated that the biofuels introduced under the RTFO will result in at least a 50% reduction in CO2 emissions. For instance a 5% biofuel (5% bio element 95% petrol or diesel) reduces CO2 emissions by about 2.5%.

To begin with most biofuels at the pump will be limited to a 5% maximum mix. This is due to the fact that most manufacturer engine warranties will currently only allow 5% biofuels to be used, although some manufacturers already allow B30 (30% biodiesel 70% diesel) to be used. Specialised "flex fuel" vehicles are already available which will allow any mix between pure petrol and E85 (85% bioethanol 15% petrol) to be used. For specific vehicle information please contact the bureau. As biofuels become more common and the bio component increased they will become increasingly important in reducing vehicle emissions. Super unleaded petrol with a bioethanol component is already available on a limited number of UK forecourts through Tesco and is distinguishable by its 99 RON rating.

LPG has been around for a number of years and has built up a strong distribution network making it a good alternative to petrol or diesel. LPG works in spark ignition engines (petrol) allowing either petrol or LPG to be used in specialised dual fuel vehicles. LPG combines the strengths of petrol and diesel. Petrol engines tend to have higher CO2 emissions than diesel's but have far lower local air quality emissions. LPG has very low local air quality emissions whilst also reducing CO2 by around 20% compared to petrol.

Natural Gas (NG) can also be used as a road fuel. It can be transported and stored in two forms, Liquefied Natural Gas (LNG) and Compressed Natural Gas (CNG). In vehicle applications CNG is usually used. CNG can provide greater reductions in emissions than LPG and is also significantly cheaper than petrol or diesel. However CNG has a poor refuelling infrastructure. Dual fuel CNG/petrol vehicles are available which make the lack of a well established refuelling infrastructure less of a problem.

Both LPG and CNG are very well suited to urban applications where local air quality emissions are of concern and noise is a problem. An engine running on CNG can be up to 70% quieter than an engine running on diesel making it ideal for use in commercial vehicles conducting night time delivers.

With the continued stepwise tightening of vehicle emissions through the EURO emissions standards, it is thought that the emissions advantage of LPG and CNG may narrow over the coming years as more elaborate exhaust after treatment technologies are fitted to petrol and in particular diesel vehicles. However vehicle gas can also be made from bio sources. Biogas is a mainstream road fuel in Sweden. Adoption of biogas in the UK could give a new lease of life to gas vehicles.