31 January 2013 Last updated at 10:01

Why don't we still drive steam cars?

By Christopher Brooks BBC Scotland

Fast, clean and energy efficient, the steam-powered car was at one time the motorist's vehicle of choice. So why did it run out of puff?

Mention steam engines and most people will think of steam trains, not steam cars.

But this has not always been the case. At the turn of the 20th century more than half the cars in the USA were powered by steam.

Mainly produced by the American companies Stanley and White, steam engines had a series of advantages over the newer internal combustion engine.

Safe and easy to drive

Steam cars in the UK

• Ownership of cars was possible for the very rich from the middle of the 19th century
• But in the UK, safety concerns and pressure from rival horse carriage services led to the introduction of restrictive laws
• The 1865 Locomotives Act limited speed to just 2 mph in towns and meant every vehicle had to have a crew of three, as well as a man walking in front holding a red flag

They were simpler mechanically, producing continuous power from steam pressure so they had no need for the transmission, clutch or gears required to harness and convert the strokes of a combustion engine.

With few moving parts, they ran quietly and could be fuelled with anything that burned.

They produced 100% of their power from rest so were also easier to drive, and safer for pedestrians. Their power could be switched into reverse at any point to reduce speed more quickly than the ineffective brakes of the time.

But steam cars also had disadvantages. They were more cumbersome than their smaller rivals, often weighing between two and three tonnes.

Substantial boilers and water tanks were needed with early steam cars losing up to a gallon (4.5 litres) of water every mile.

Stanley partially remedied this with the introduction of condensers in 1915, which turned much of the steam back to liquid water before it could escape. But even then they were still only achieving eight miles per gallon of water.

Another drawback was how long it took to build up steam pressure before a journey could begin.

A Stanley steamer owner's manual published in 1918 suggested that this would take between 10 and 15 minutes, but in cold weather it was likely to take much longer.

Starting had also been an issue for cars powered by the new combustion engines. Early models required hand-operated cranks to start which could break arms and wrists when the car backfired.

But the invention of the electric starter gave the internal combustion engine an advantage and led large manufacturing companies to invest.

Overtaken by rivals

2009 land speed record

• In 1906 the Stanley steam car "Rocket" set a land speed record of 127.66 mph
• It was the last time a steam car would hold the overall record and was beaten in 1909 by a Benz car with an internal combustion engine
• In 2009 a British team set a new record of 139.843 mph, an improvement of just over 12 mph in 103 years
• The overall land speed record of 763.035 mph was set by jet car "Thrust SSC" in 1997

• The British record attempt

By 1910, cars with internal combustion engines were being churned out in huge numbers at prices so low that the smaller steam car manufacturers had no chance of matching them.

Soon, the Ford Model T took the Stanley's crown as the most popular car on American roads.

Steam car makers adapted to their marginalisation, marketing their cars as luxury products. Stanley took out newspaper adverts emphasising the "soft, smooth, gliding motion," to help readers "[recognise] the fundamental superiority of steam," as they put it.

But by 1918 the Stanley Steamer was almost six times the price of a Model T.

The Stanley Company declined and eventually stopped trading in 1924, by which point steam cars were considered a rare and antiquated novelty.

Since then, steam cars have all but disappeared from roads. However, many have been preserved by enthusiasts like Alun Griffiths, Secretary of the Steam Car Club of Great Britain, who owns a 1916 Stanley Steamer.

"[I hear] the wind whistling in the hood fittings and no other sound apart from a faint thump, thump from the feedwater pumps, like the beat of the machine's heart,"

"It has been said of steam cars, and of steam engines generally, that they seem alive compared to other pieces of machinery, and I can only agree with that."

Future use

But are steam cars consigned to the past, a now obsolete stepping stone in automotive history? Perhaps not.

Internal combustion engines have their own inherent drawbacks. They depend on fossil fuels, a finite resource likely to become ever more expensive. And they produce pollutants including carbon monoxide and nitrogen oxides.

The last great steam car

• In 1925 the Doble E steam car addressed almost all of the problems of early steam cars
• It reduced start-up time to just one minute, condensed water efficiently for re-use and managed 15 miles per gallon of cheap kerosene fuel
• It was also fast, managing 0-75 mph in 10 seconds with a top speed of over 100 mph
• Designer Abner Doble was a perfectionist and tinkered with the design - no two models Es were quite the same
• Fewer than 50 were made and full production never began

Steam cars could use a range of fuels and their continuous power- available even when they are at rest - lends itself to modern traffic, with only light touches of the throttle and brake needed to stop and start.

Modern technology could reduce many of the historic problems of steam cars. Lightweight materials and heat resistant coatings could drastically reduce the weight of the boiler and condenser, and water retention could be maximised. Start times with modern boilers could be reduced from minutes to seconds.

Some car companies have researched and developed steam technology over the years, most notably in the 1990s with the Volkswagen spin-off, Enginion AG. This was a steam engine with efficiency comparable to modern internal combustion engines with lower emissions.

Since then, Cyclone Technologies has developed a new steam engine which it claims is almost twice as efficient as an internal combustion engine.

As yet neither of these engines has been put into a production car, so is there any chance the steam car could make a return onto our roads as a modern, consumer vehicle?

As internal combustion engine's deficiencies become more apparent a market may emerge. "If a committee was faced with a clean sheet and the choice of a steam or a diesel future, they might decide that steam was a better way forward," said Roger Kemp, Professor of Engineering at Lancaster University specialising in energy safety of transport systems.

"But we are not in that position, the petrol/diesel car business must be one of the biggest industries in the EU and I can't see a strong argument for the huge shakeup that would be required to convert to steam power", he added.

So it seems that steam cars will remain only in the hands of enthusiasts. But even if steam power never returns to our roads, it will remain an important part of transport history.

Learn more about the inventions that helped build modern transport in episode two of The Genius of Invention on BBC Two on Thursday 31 January at 21:00.