A Good Life 





Proud Co-Founder of Transition Town High Wycombe


Proud Member of the Low Carbon Chilterns Cooperative



Proud owner & retrofitter of Superhome 59

Superhome 59


This website proud host of the High Wycombe Local Food Guide

Local Food



Our Post-Carbon Home should be so good that you never want to leave it. However, we are all caught up in the paradigm of consumer culture, work and paying for mortgages so most of us have to leave the house eventually. There isn't really that much round these parts so you can walk for a while without reaching anywhere useful. The nest step up is a bicycle however we live on one of seven hills that dominate this town. Cycling is for those who like self-punishment, not light exercise. Sadly, and inevitably you end up in a car. You keep the miles down but it remains an essential tool for Business Travel with luggage and flexibility built-in. Busses and trains don't quite cut it - as much as we wish they would. So, if you end up having a car, what is the best option? Well, here is what we chose and why.

In the Garage

We have been using LPG-powered cars since 2005. The reasons are clear and we shall explain them again here as we have also done so over in our LPG Cars section. Liquid Petroleum Gas-powered cars yield annual CO2 savings of 16% over petrol whilst hydrocarbon (soot) emission are down by 40%. The NOx emission savings are 80% whilst Carbon Monoxide emission savings are 35%. So it is clean - very clean. However, it is still using fossil fuels. Peak Gas is much further off than Peak Oil and many pundits (ourselves included) see Gas as the perfect "transition fuel". LPG is produced as a by-product in both the extraction and refining stages of oil production. In the past it has been considered waste and flared off. It is particularly abundant in the North Sea's 'wet' crude oil. Consequently the UK is Europe's largest producer, producing 6.4 million tonnes in 2001. Of this over 3 million tonnes were exported. Only 50 thousand tonnes (7.75%) were used as Autogas. The rest was used for domestic or agricultural heating or in chemical or refinery operations. Liquefied Petroleum Gas (LPG) is a mixture of Propane and Butane. When used as a Vehicle Fuel it is often referred to as "Autogas".


A vehicle that runs on BOTH Petrol and LPG is termed 'dual-fuel'. It starts on Petrol until warm then automatically switches to gas. With Mileage of about 7,000 per year the reduction in annual fuel costs are around £1000 due to the lower Tax on LPG. Installation costs (+ value added tax) were £2,200. Payback period is 2 years. Some Cars qualify for a grant in the UK (as well as exemption from Congestion charging) plus you also get a reduction in your annual Car Tax. Annual Car Tax on the "alternative fuel" Toyota Aygo in 2010 was just £15. The Insurance premium is under £200 per year fully comprehensive. The Toyota Aygo is rated at 108g/km CO2 but the LPG reduces this to 92g/km. Hence the Aygo is cheap to run and yields extremely low emissions. Not all Cars have as much space under the bonnet as this small car. Hence, if you are considering a dual-fuel installation make sure that you have a bit of space up front. Having said this, the LPG equipment takes up very little space. Most, if not all cars that currently use Petrol can be converted.


Installation will not invalidate your Warranty so you can still get your car maintained at your local dealership. Autogas requires a pressurised cylinder to hold a supply of LPG in addition to your normal petrol tank. Here we see the boot with the tank in the spare wheel well. There is space for a tank holding 30l gross although you can only fill it up to about 27l. This will yield up to an approx 240 miles of range. In July 2010 you could fill the tank at a motorway service station for about £18. Choose a far cheaper option such as a major Supermarket in the UK (Asda is good) and this cost will drop to about £14 for a full tank. This is really cheap motoring. THIS car obviously has no spare so utilises a pressurised foam can for emergencies. The positioning of the 'donut' tank in the spare wheel well leaves the entire boot space free. Although the Toyota Aygo is a micro-compact there is space in this boot for one large piece of luggage and a laptop computer bag. The simple chemical make up of autogas ensures that it is clean burning. The engine is quieter and lives longer.


So, where do you fill the tank? It varies from fit to fit but most cars simply have a filler cap co-located with the petrol cap. This is not possible on all cars and on the Aygo we had it discretely fitted under the rear bumper with all LPG piping running under the car. The LPG flows into the tank via a small hole in the middle of the spare wheel well. How do you know it is full? Well the Autogas pump simply stops pumping - much as with petrol. There is a small addition to your dashboard - a small fuel gauge using small LED's. These are only a rough indicator and drivers familiar with LPG keep an eye on mileage as a better indicators of when to next fill up. This small combined indicator and switch shows how full the gas tank is and allows you to switch over to petrol manually. However, this is rarely necessary. You treat your petrol tank as your "spare" which can actually yield 400 miles of range if you leave it full up. Of course you don't leave it full up as that means having to haul around a tank of petrol all the time. So you only leave it one-quarter full to get better performance.


So, consider the challenge: you have a Carbon-Neutral Home, don't fly and consume the barest minimum. How do you get your direct carbon footprint down to one tonne? With emissions of just 92g/km and 1,000,000gm of carbon to play with gives you an annual range of 10,870km or 6800 miles. Of course this is highly simplistic but you can have low-carbon transport. To go any lower you need to switch fuels and move over to electricity... But that is another story.


So load your Aygo with four people and you get 23g/km/person. Compare this to Full Transatlantic Cruise Ship = 1611, Short Haul Flying = 250 to 300, Long Haul Flying = 201, Motorbike = 107, Bus = 89 and Rail = 60. Some might argue with these numbers but the ball-park figures speak volumes. Is it possible to drive a car and look down upon public transport? Possibly, but that is not the point of this exercise. There is no such thing as an environmentally friendly car and their days are numbered. The amount of metal and plastic per person is unacceptable in the long term. Then there is all that road space and their wider social impacts. Cars are not the spawn of the devil. Lots of cars are. Car culture is. If you don't need a car don't have one. We recognise that isn't quite yet possible for many of us. If you must have one - choose wisely.


Low Carbon Man

  • There is no such thing as an environmentally friendly car. LPG conversions are also expensive.

  • This really does pay for itself and cuts your carbon. If you need a car then this is your best bet if you don't need a big car.




References: References