Author: Dr Daniel Coren CEng MIMechE FHEA, Director of Studies for Automotive MSc Courses
In this fourth post in the series, Daniel discusses how we moved from horse-drawn carriages to cars, the evolution of safety and comfort, and the influence of culture on the industry.
As motive power moved from horse to electric machines, and steam or internal combustion engines, a means of rating and comparing them was needed. Aptly, the definition of an engine's capability to produce useful mechanical power referenced the source of power it replaced. A machine that can lift a 75kg mass one metre in one second, when subject to Earth's gravitation was considered equal to the power of one horse. As such, one Chevaux-Vapeur is equal to approximately 735 Joules per second. Or one metric CV is equal to 735 Watts. Note that one imperial ‘HP’ is equal to approximately 1.01 CV! None of this is to be confused with ‘tax horsepower’, which is based on engine geometry rather than actual power output. One example of this is the French Fiscal Horsepower rating, Chevaux Fiscaux, (confusingly, also known as CV) which gave rise to the road-going and ploughed-field-ready Citroen 2CV (which actually had about nine HP).
With new opportunities for untethered adventure, exploration and freedom of movement, came the tariff of hidden threats. This was mainly in the form of air pollution but also included congestion and safety. To continue the equestrian theme - is the car a modern-era Trojan horse?
A breath of hot air?
Progress in automotive technology has helped reduce pollution in the past as well as the present. In 1900 there were 3.45 million horses in the UK leading to 'The Great Horse Manure Crisis'. There are ten times more cars today (and twice as many people). We have largely rid the streets of pollution in the form of horse waste but sewn seeds for another one less visible but global.
European emission standards for petrol cars reduced CO emissions from 2.72 to 0.5 g/km between 1992 and 2025. CO2 was reduced from around 150 to 95 g/km between 2000 and 2021. In 1902, tarmacadam began to reduce the dangerous plumes of road dust but Marcel Renault died in the 1903 Paris to Madrid race when a dust cloud obscured a tree. New legislation aims to cut down particulate emissions of nanometre scale from brakes and tyres. The 2015 emissions debacle shone a light on how things can go wrong but lessons learnt have been a catalyst for change. Now we have more realistic drive cycles in the 2017 Real Driving Emissions (RDE), and the 2018 World Harmonised Light Test Procedure (WLTP). There is an emphasis on the ability to recycle batteries as part of the Euro 7 standards. We're also watching the growth in the electric vehicle market share in real-time. And sustainable fuels and hydrogen are now more commercially available too. The latter in a rainbow-range of colours to denote environmental credentials.
A bumpy road
Moving at speed on roads intended for horse-drawn carriages could be tiring. Chevrolet was an early adopter of independent coil spring suspension for road cars. Their promotional films showed model cars with pen traces on graph paper to highlight the gains in comfort. Not to be outdone, Citroen used imagery of smooth headlight traces to show off the self-levelling characteristics of their hydro-pneumatically suspended 1955 Déesse (goddess). The challenge of balancing ride comfort with handling characteristics carries on. In a nod, Mercedes called the adaptive damping of their 2013 S-Class 'magic body control'. And motoring journalists still sometimes refer to Lotus sports cars as being able to 'breathe the road'.
Sitting comfortably at speed brings safety to mind. Saab was the first company to fit seatbelts as standard fitment in a production road car, in 1958. In 1959, Nils Bolin invented the modern three-point safety restraint for Volvo. The Bugatti Chiron has six airbags as standard. The result? Road deaths per billion road miles travelled in the USA fell from around 300 in 1920 to 8.3 in 2021.
A factor in this reduction is the advancement of tyre technology. Just down the road from Bath, Bradford on Avon is the home of the UK rubber industry. In 1848 a factory was built to apply the techniques developed by Charles Goodyear. This included the manufacture of tyres for cars and motorcycles. Michelin bought the bankrupt Citroën in the 1930s. The 1948 Citroën 2CV was the first car designed with radial-ply tyres to improve directional stability and reduce rolling resistance. This was adopted more widely by European manufacturers throughout the 1960s, and in the USA during the 1970s. Autonomous vehicles promise to reduce this further still. Digital is being used to mitigate errors stemming from fatigue, but also to reduce road congestion.
Dream machines or technicolour schemes?
Henry Ford once said: “Any customer can have a car painted any colour that they want, so long as it is black”. This colour was a consequence of using a paint application process called Japanning, which was fast, cheap and durable. But this limited choice did not suit everyone. Seeing an opportunity, General Motors partnered with DuPont resulting in an explosion of colour in the 1920s and 30s. A sort of 'curate your own car' approach took off. At the same time, Mondrian and Kandinsky were experimenting with colour. And the De Stijl and Bauhaus movements were gaining traction, building on works such as Goethe's Colour Wheel (1809) and Newton's 'Opticks' (1704).
You could consider this as an early example of today's online virtual vehicle 'configurators'. Or how clever business management uses the influence of artistic expression on human behaviour and decision-making to its advantage. You can see it in car adverts today. They have grown more sophisticated and often focus on lifestyle aesthetics as much as technical merit. This 'high-tech art on wheels' reflects ever more our connected lives.
The idyll of the open road has brought some unwanted side-effects. What will future generations expect from a car? What unintended consequences and challenges might they face?
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