Open Engineering
Environment and Development.


In the rich industrialised parts of the world, most families own a car. It is the dream of many families in the rest of the world to do the same and car ownership is growing fast in China and India. But soon car ownership is likely to peak and then decline because there are simply not enough resources to sustain further growth. Because of the contribution of cars to climate change, we should WANT this to happen! So for the majority of the world's population, we need to find low-energy, low-carbon and cheaper alternatives to cars. [Cambia a la versión en ESPANOL]

Cars Are Not The Future

The private car can NEVER provide transport for the majority of the worlds population. There are three reasons for this:

Rich countries are trying to deal with the problems of climate change and oil shortages by designing cars that use less fuel. But these vehicles are expensive, sometimes costing more than current models. They also still cause substantial (and probably unsustainable) environmental damage because of the energy and resources needed to manufacture them. So cars will continue to remain out of reach for the majority of the world's population. Policy makers in poorer countries who invest in road schemes for cars must recognise that they are spending public money to support the unsustainable habits of an elite. Of course such policy makers will often be among the privileged few who own a car - but that need not prevent them, if they wish to act responsibly, from investing public money in alternatives. In the richer countries, environmentalists should and do campaign to reduce car ownership and use.

There are other reasons to reduce car usage: they make our towns unpleasant and stressful, killing at least 3 million people a year [See: Humanity's Worst Predator]. Perhaps one day the world's population will fall to a manageable level and new energy sources will be developed, making it possible for everyone to own a car ... if that's what humans really want. But for the moment, cars are taking us along a road to disaster.

Saving Travel

Reducing the need to travel would save energy. In Britain the average distance a person travels every year (excluding air travel) has gone up from 1000 miles fifty years ago to 6800 miles today. Almost all of the growth is in car travel. The location of shops and workplaces has adjusted to the fact that cars allow people to travel further. The average journey to work in the UK has gone up from 2.5 miles in 1980, to 7.2 miles in 1990, to 8.7 miles in 2006. That 8.7 mile trip can take from a half to one hour because average traffic speeds are so low. Some commutes are so long that people are spending a third of their salary and almost half their day on travelling. By comparison, a 2.5 mile journey to work by bicycle takes just 12 minutes and costs almost nothing.

Ways of reducing the need to travel:

Cycle Freeways

The bicycle is probably the only personal vehicle that could be affordable for all and would not wreck the environment if everyone had one. Yet few countries invest in facilities for them.

The cheapest and most flexible transport system for even quite large cities (like London) provided that they are not too hilly, would be the construction of a network of cycle 'freeways' (straight, clear routes, free of cars) and supporting infrastructure such as secure parking areas. Such a system offers:

(1) Everyone could own a Bike! (2) Bicycles need safe routes. (3) Bicycles Carry. (4) Bicycle Mass Transit.

Energy Used by Transport

In environmental terms, cycle freeways are better than all other forms of land transport. The energy used per passenger mile by various forms of transport is shown in the table, with three common units of energy:


Energy Used per Passenger Mile (1mile = 1.6km)

Bikes for the Old

Bikes for the Young

Bikes for Luggage

Flexible Bikes

For comparison: To boil kettle requires about 0.06kWh for 0.5 litres of water. A typical fridge-freezer uses about 1.5kWh per day.


For more details and References, see:Cycle Freeway.

Innovative Public Transport

The city of Curitiba, Brazil has a 'Bus Rapid Transit' (BRT) system, which offers many of the features of a metro at a fraction of the cost. The buses run frequently—some as often as every 90 seconds—and reliably, and the stations are convenient, well-designed, comfortable, and attractive. Consequently, Curitiba has one of the most heavily used, yet low-cost, transit systems in the world. It offers many of the features of a subway system—vehicle movements unimpeded by traffic signals and congestion, fare collection prior to boarding, quick passenger loading and unloading—but it is above ground and visible. Around 70 percent of Curitiba’s commuters use the BRT to travel to work, resulting in congestion-free streets and pollution-free air for the 2.2 million inhabitants of greater Curitiba. See: Curitiba

Light Rail systems are available that are cheaper than conventional rail because they use automotive and tram type technology. Some examples:, parrypeoplemovers. In the late 1970s, trade union members in the British company Lucas, converted a bus to be a 'road-rail bus', in conjunction with a college. The standard road tyres run on both road and rails. Small retractable guide wheels ensure the vehicle remains on the rails. The aim was to suggest alternative more socially valuable products to the company and maintain employment.

(1) Modern Light Rail. (2),(3)&(4) Road-Rail Bus built as a union initiative.

Electric and Solar Vehicles

The car industry proposes to replace conventional gasoline/diesel cars with electric cars of a similar size and speed. These vehicles are likely to be just as expensive to produce in terms of money and CO2, as conventional cars. In operation, if the electricity they use to charge their batteries comes from fossil fuelled power stations, they may actually consume more energy and produce more CO2 than a conventional car. Therefore, electric cars are only a benefit if they are used within a country with a large surplus of renewably generated electricity, or if they are ultra-low energy vehicles which means lightweight and low speed, such as the electrically assisted pedal vehicles described below.

Lightweight electrically assisted pedal vehicles that are similar in speed and construction to bicycles could supplement normal bikes. They would be far less damaging to the environment than conventional cars and far cheaper to buy and run (the cheapest electrically assisted bikes are about $500 US). To be pleasant to use, they would need to be segregated from existing traffic but could share bicycle freeways.

Electric Bike:

  • 800-2,000mpg (290 - 700 kilometres/litre).
  • $500 to buy (From: $300 to $2000).
  • Cost per mile: $0.08 (very little electricity, but batteries need replacing).
  • [Compares $0.80 to $1.00 cost per mile of a car].

An electric bike achieves about 800-2,000mpg (290 - 700 kilometres/litre). No other commercially available vehicle can match figures of this kind. The mpg of an electric bike is actually higher than the estimate for normal pedal bikes. That is because of the energy that goes into providing the extra food you eat to pedal the bike; by comparison the direct conversion of sunlight to electricity in a solar panel is more efficient. See: Bike Energy Article, and However, with any powered vehicle you tend to travel more than if you have to pedal yourself, so a society that used electric bikes might still use as much or more energy than one that used pedal bikes.

Electrically assisted pedal bicycles are already widely available and could readily by charged from renewable energy sources.

Some electrically assisted vehicles incorporate solar panels. An example of such a vehicle is this solar tricycle: which can travel at 6 to 8mph using the solar panel alone, without pedalling or battery power. Two larger 4-wheel vehicles:, A list of solar vehicles is here:

(1) An Electric Bike. (2) Electrically Assisted Bike with PV panel for solar charging. (3) The Solar Trike.

But If You Must Have a Car ...

If you are buying a car, pay less for fuel and minimise your impact on the environment by buying the most efficient you can get. Several family-size diesel cars achieve better than 60mpg under real driving conditions, BUT if you live in a town or city using a diesel is more anti-social than petrol because of the higher emissions of NOx and much higher emissions of particulate matter. A petrol hybrid can also achieve high efficiencies because when the batteries require charging, the petrol engine is run under its optimum load conditions; when the batteries don't require charging, it is switched off. A 'plug in hybrid' also allows you to charge the batteries from the electricity grid as you would with an all-electric car, and so for short journies the petrol engine may not need to run at all. Use the links below to identify efficient models.

The fuel consumption of private cars varies from less than 15 miles per gallon (mpg) to over 80! Or in litres per km, from about 5 l/km to 28 l/km [Imperial gallon (UK) is 4.546 litres, US gallon is 3.785 litres]. Motor manufacturers are required to publish the fuel consumption of their vehicles. Governments maintain databases of vehicle fuel consumption which can be accessed on-line: UK:; US:

The average fuel efficiency of cars in the USA is 22.4 mpg, and 18 for pick up trucks (]. In Europe the average for cars is much higher - about 40 mpg.

Jeep Grand Cherokee 6.1 SRT-8

BAD: 17.5 mpg

GM Astra 1.7CDTi ecoFLEX

LESS BAD: 62.8 mpg BUT better to get a hybrid than a diesel

High Performance Vehicle

BRILLIANT: 885 mpg equivalent


Growing crops to produce petrol or diesel is being promoted in Europe and the USA, but is also strongly criticised on the grounds that:


Waste oil from cooking can be turned into biodiesel and it can be done on a very small scale. This would seem to be environmentally benign in terms of CO2 emissions, but the emissions of NOx and particulates still make diesel undesirable. Lots of information is available on the web

Detailed instructions in English and Spanish on Also in English & Spanish: