Building blocks
Although it is starting to fall out of favour, the internal-combustion engine has been the dominant power source for cars over nearly 140 years.
The basic principle of the ICE is that it consists of one or more devices which turn a crankshaft, which turns a flywheel, which turns a sequence of gears, which turn the road wheels, allowing the vehicle to move.
Upstream of the flywheel, decisions have to be made about how many devices (usually but not always pistons) there should be, and, if the answer is more than one, how they should be arranged.
That’s what we’re going to explore here, looking at all the possibilities and giving examples of each one being used.
What follows are 25 engine-configuration variations seen in roadgoing production cars – plus a few bonus motors that don‘t quite fall into that category.
1. Single-cylinder
Carl Benz’s Patent Motorwagen, widely regarded as the world’s first car, was powered by a simple engine with just one cylinder.
This configuration keeps costs down, because it involves very few moving parts, but does not score well for refinement.
Since the former is much more important than the latter in extremely cheap cars with minimal performance, single-cylinder engines remained in use for a remarkably long time.
They were particularly suitable for bubble cars such as the BMW Isetta (pictured), which was still being produced in the early 1960s.
2. Single-rotor
Rotary engines have far fewer moving parts than ones with pistons, and are notable for their refinement and power output, but unfortunately also for low economy, high exhaust emissions and, in the early days, terrible reliability.
The first rotary car sold to the public was the NSU Spider of 1964 (pictured), which had just one rotor.
Citroën opted for the same configuration in the reasonably successful M35, a predecessor to the calamitous GS Birotor.
The M35 was never sold to the public, but more than 200 were made available to existing Citroën customers for evaluation between 1969 and 1971.
Mazda currently uses a single-rotor as a ‘range extender’ (generating electricity rather than driving the car) in its MX-30 SUV.
3. Inline-twin
Daimler was the first company to mount two cylinders side by side in what has become known as the Schroedter car (after its designer Max Schroedter), of which a dozen were produced from 1892 to 1895.
One of these was the first Daimler car ever sold to a private customer, the customer in question being Sultan Hassan I of Morocco.
Perhaps the most famous of the many inline-twin cars which followed it was the Fiat Nuova 500 (pictured), manufactured from 1957 to 1975.
Very much against the current trend, Fiat returned to the layout in 2010 with the TwinAir engine, which appeared first in the contemporary 500 and subsequently in other Fiat, Alfa Romeo and Lancia models.
4. Flat-twin
Like all engines with horizontally opposed cylinders, the flat-twin has an advantage over its inline equivalent in that it is very low, keeping the car’s centre of gravity nearer the road surface.
Lanchester had a flat-twin car running in 1896 at the latest (and possibly 1895), but didn’t put one into production until 1900, by which time Benz had had been selling models with what it called ‘contra’ engines for two years.
For its entire, and very long, production run, the Citroën 2CV (pictured) was powered by a flat-twin engine available in various capacities from 375cc to 602cc.
That engine was also used in 2CV derivatives – Ami, Bijou, Dyane and Méhari – while a more modern 652cc unit of the same layout was fitted to the Citroën Visa and LNA.
5. V-twin
The designer of a V engine has to decide at an early stage what the angle between the cylinders on each bank should be, an issue which does not arise in flat or inline motors.
Despite this extra complication, the V-twin was the first type of two-cylinder petrol engine ever fitted to a car.
Daimler’s prototype Stahlradwagen (translated variously as ‘steel-wheeled car’ or ‘wire-wheeled car’) was displayed at the Paris World Exhibition in 1889, and its V-twin engine was put into production shortly afterwards, in some cases being built under licence by Panhard.
The first production Peugeot (the Type 2 of 1890) used the Panhard-built Daimler engine, while Mazda’s first passenger car (the R360 of 1960) also used a V-twin, though Mazda designed and built this itself rather than buying it in from anyone else.
Large V-twin engines originally intended for use in motorcycles were fitted to three-wheeled Morgans from 1911 to 1939 (Super Sports pictured), and then again from 2012 onwards.
6. Twin-rotor
Nearly every rotary-engined car ever built, starting with the 1967 Mazda Cosmo, has had two rotors.
With sales exceeding 400,000 units, the first-generation RX-7 (pictured) is not only Mazda’s most successful twin-rotor model, but the most successful car with any rotary engine produced by any manufacturer.
Less happily, early reliability problems for the Ro80 effectively brought the NSU brand to a standstill (even though the car was produced for around a decade), and the Citroën GS Birotor was a complete disaster.
In the early 1970s, General Motors partially developed a twin-rotor engine intended for the Chevrolet Monza, the Chevrolet Vega and, through a business arrangement, the AMC Pacer, but the programme was abandoned before any of them went into production.
7. Inline-three
Two-stroke inline-threes started to appear in the 1950s, powering the DKW Sonderklasse, Saab 93 (pictured) and Wartburg 311.
In later years, four-stroke versions were popular among Japanese manufacturers, which used them often, though not exclusively, in kei cars.
Inline-threes generally have small capacities, but a startling exception was the VM Motori 1.8-litre turbodiesel fitted to the Alfa Romeo 33.
This was the largest production inline-three until Koenigsegg developed its 2-litre Tiny Friendly Giant (used in the Gemera), which has no camshafts and produces vastly more power than any other car with an engine of this configuration.
In the second decade of the 21st century, several manufacturers developed turbocharged inline-threes which have been used in models as diverse as the Ford Fiesta, Dacia Duster and Toyota GR Yaris.
8. Triple-rotor
Triple-rotors are extremely rare, but their history is almost as long as that of single- and twin-rotor engines.
Units with this configuration were used in early examples of the Mercedes-Benz C111 experimental sports cars, starting in 1969, but they were soon abandoned, and no production Mercedes has ever been powered by a rotary engine of any sort.
Mazda, in contrast, developed a triple-rotor for the last car in its Cosmo series, which was sold in the first half of the 1990s and was marketed as part of the luxury Eunos brand.
The Eunos Cosmo was also notable for having twin turbochargers, and for being an extremely early example of a car fitted with satellite navigation.
9. Inline-four
Although it’s impossible to say what was going on in other workshops around the world in the late 19th century, the first inline-four car engine may have been the one fitted to a US-built 1895 prototype called the Buffum Stanhope.
The configuration later became so popular that attempting to choose a single car to illustrate it verges on the reckless.
We’re going for the Ford Model T, partly because it held the global production-car record from 1927 to 1972, and partly because it was named Car of the Century in a poll whose results were announced in December 1999.
Perhaps significantly, the second and third cars on that list – in order of votes cast, the Mini and the Citroën DS – were also powered by inline-fours.
10. Flat-four
Volkswagen used nothing but air-cooled flat-four engines in its vehicles between the introduction of the Type One (commonly known as the Beetle) in 1938 and that of the NSU-developed K70 32 years later.
Along with four-wheel drive, a water-cooled flat-four engine – often turbocharged – has been a mainstay of Subaru models for many years, most notably in the Impreza road and rally cars.
Porsche produced a flat-four derivative of the 911 called the 912 in the late 1960s, and sold a similar model called the 912E in North America in the 1976 model year only.
Porsche then returned to the configuration for the 982-generation Boxster and Cayman in 2016, only to find that the cars were criticised for not sounding like ‘real’ Porsches.
11. V4
More loyal to the layout than any other manufacturer, Lancia produced cars with V4 engines from the introduction of the Lambda in 1922 to the discontinuation of the Fulvia (pictured) in 1976.
Unlike most V-engines, the Lancia V4s had their cylinder banks at such a narrow angle that a single camshaft could be used to operate all the valves.
Ford of Britain and Ford of Germany both developed much wider-angle V4s in the 1960s, and fitted them to vehicles including the Capri, the Corsair, the Taunus, the Zephyr and the Transit van.
The German version was also used in the Saab 96 saloon and its 95 estate equivalent, the Matra 530 and – perhaps strangest of all – the mid-engined Mustang I concept car of 1962.
12. Inline-five
The first production inline-five was a 3-litre diesel fitted to the 114-series Mercedes-Benz 240D in 1974.
Engines of this configuration have also been used by Fiat, General Motors, Honda and Volvo, the last of which provided the units for the high-performance ST and RS variants of the second-generation Ford Focus.
However, Audi is the brand most closely associated with the inline-five, which it started offering in the 100 in 1977 and is still using today.
Despite the earlier arrival of the 100, the most celebrated five-cylinder Audi is the quattro, which was launched in 1980 and almost immediately transformed the sport of rallying, thanks to the combination of its immensely powerful 2.1-litre turbocharged engine and four-wheel drive.
13. V5
The Volkswagen Group is the only car manufacturer to have used a V5 engine in a production model.
Like the Lancia V4 and VW’s own VR6, this motor (known as the VR5) has an extremely narrow angle between the two cylinder banks, so only one cylinder head and one camshaft were required.
The obvious difference is that the VR5 has an unequal number of cylinders in each bank, two on one side and three on the other.
The VR5 was offered in several VW Group cars based on the same platform – the fourth-generation Golf, its saloon derivative (known as the Bora or Jetta depending on where it was sold), the New Beetle, and the Seat Toledo – and in the larger Volkswagen Passat.
14. Straight-six
Notable for their excellent balance and refinement, straight-six engines have been designed and built by a great many manufacturers.
Among more examples than you can shake a stick at, the configuration has been used in the Rolls-Royce Silver Ghost, the first-generation Chevrolet Corvette and several MG sports cars of the 1930s.
The longest-lived engine of this type is the Jaguar XK, which first appeared in the XK120 and was later used in the E-type (pictured), the XJ6, the Daimler DS420 limousine and many other vehicles, including sports-racers built by specialist manufacturers.
The straight-six eventually became less popular than the more compact V6, and was abandoned by most marques, with the notable exception of BMW.
15. Flat-six
The most enthusiastic adopter of the flat-six engine is Porsche, which has used it in every generation of the 911 and in other models such as the Boxster, the Cayman and the 914/6.
British manufacturer Wilson-Pilcher produced a car with a 4.1-litre straight-six, though you can be forgiven for not knowing about it because the brand folded more than a century ago.
The layout is very rare in North America, but it was used in the Tucker 48 shortly after the Second World War and in the Chevrolet Corvair throughout the 1960s.
Subaru, best known for its flat-fours, has also produced flat-sixes (for example in the Legacy and Outback), when a larger engine is required.
16. V6
Delahaye developed a V6 engine for its Type 44 before the First World War, but the configuration did not become popular until after the Second.
Lancia fitted its first V6 to the Aurelia in 1950, and within a few years engines of the same type were being produced in great numbers around the world.
Even Ferrari, better known for its V12s, created a V6, which was used both in its own Dino models and in the dramatic Lancia Stratos (pictured), the winner of the World Rally Championship three years in a row from 1974 to 1976.
As mentioned previously, the Volkswagen VR6 engine was a narrow-angle V6, similar in concept (if not in number of cylinders) to the same company’s VR5 and Lancia’s V4.
17. Straight-eight
Eight is the highest number of cylinders arranged in a single line in engines intended for use in production cars.
After a brief flurry of interest in the late 1910s and early 1920s, the V12 engine became temporarily unpopular in North America, where manufacturers decided en masse that the simpler straight-eight was the most appropriate engine for high-quality cars.
Packard, the V12 pioneer in that part of the world, followed the new trend, and produced the first in a series of straight-eights (pictured) in 1924.
In Europe, Alfa Romeo, Bugatti and Mercedes produced memorable straight-eights, but as with the American engines their very long crankshafts became thought of as a disadvantage, and the configuration was largely abandoned in favour of the much shorter V8.
18. V8
V8 engines have eight cylinders arranged in two banks of four, and are particularly associated with North American manufacturers, though many have also been developed in Europe and, to a lesser extent, other parts of the world.
Cadillac is usually credited with giving the configuration its debut in production cars, but Ford’s flathead V8, manufactured for more than two decades, brought it to the mass market.
The Chevrolet small-block V8, originally fitted to the first-generation Corvette (pictured) and second-generation Bel Air, and still available in ‘crate’ form, has been produced in enormous numbers – according to General Motors, the 100 millionth example was built in 2011.
Rover’s all-aluminium V8, based on a design by Buick, survived well into the 21st century, having made its debut in 1967, and was fitted to models produced by Rover itself, Ginetta, MG, Morgan, Triumph and TVR.
19. W8
In contrast to the V8, the W8 is essentially two V4 engines mounted side-by-side and driving a single crankshaft.
Theoretically, it can be shorter than an inline-four, but it is also extremely wide, which can cause packaging problems.
Volkswagen fitted a 4-litre W8 to a luxury four-wheel-drive version of the Passat from 2001 to 2004, which was possible because the engine in every Passat of that generation was mounted longitudinally.
In the next generation, engines were mounted transversely, which meant the W8 wouldn’t fit.
No other manufacturer has used a W8 engine before or since, and it now seems unlikely that any ever will.
20. V10
Chrysler has been the manufacturer most faithful to the V10, which it used in the Dodge Viper (pictured) from 1992 to 2017 (with a pause from 2010 to 2013).
Apart from that, US companies have generally used the V10 in trucks and commercial vehicles, rather than passenger cars.
The situation is different in Europe, where Audi, BMW, Lamborghini and Porsche have all fitted V10s to high-performance sports models.
Japan’s only production V10 was a 4.8-litre unit co-designed by Toyota and Yamaha, and fitted to the Lexus LFA coupé.
21. Flat-12
The low centre of gravity offered by a flat-12 engine inspired Alfa Romeo, Ferrari, Mercedes, Porsche and (unsuccessfully) Subaru to use it in motorsport applications.
Of these, only Ferrari went a step further and offered flat-12s in roadgoing cars, too.
The first, initially measuring 4.4 litres, made its debut in the mid-engined 365GT4 BB (pictured) in 1973.
Ferrari would later increase the capacity to 4.9 litres and use four valves per cylinder, in which form the engine was still being used in the Testarossa up to the point where that car went out of production in 1996.
22. V12
The first V12 engine was built by the Putney Motor Works for a powerboat in 1904, while the first car to use one (with cylinder deactivation!) was the one-off Schebler of 1908.
Seven years after the Schebler, Packard became the pioneer of V12 production cars with its Twin Six.
Many other manufacturers followed, but the one most closely associated with V12s is Ferrari, which has used them in a great many cars, including the 250GT SWB pictured here.
The 250’s engine was designed by Gioacchino Colombo and had an extremely long production life.
It made its debut in the 125 S racer of 1947, and was still being used (after a substantial amount of development) in the 412i 41 years later.
23. W12
A W12 engine can have either three banks of four cylinders (a formation known as the ‘broad arrow’) or four banks of three.
Volkswagen went for the second option when it developed the only W12 designed for a production car, which it effectively did by joining together two of its existing narrow-angle VR6s.
Although its layout is very unusual, the engine has been used for more than 20 years in a wide variety of Volkswagen Group models, starting with the Audi A8 in 2001.
It has since appeared in the Bentley Bentayga, Continental and Flying Spur (pictured), and the Volkswagen Phaeton and Touareg.
24. V16
In 1930, Cadillac became the first of only three manufacturers to use a V16 engine in a road car offered for sale to the public.
Producing such a complex device was amazing, but not as amazing as the fact that Cadillac replaced it with another, very different V16 eight years later.
The Marmon Sixteen, whose name gives away the type of motor it had, was produced in smaller numbers in the early 1930s.
Even rarer than the Marmon was the Cizeta V16T, a 1990s sports car with a V16 engine consisting of nearly enough parts to build two separate Lamborghini V8s.
25. W16
In typically innovative style, the Volkswagen Group created the only W16 engine ever fitted to a production car.
The 8-litre motor, officially known as the WR16, first appeared in the Bentley Hunaudières concept in 1999, and then in the Audi Rosemeyer the following year.
Among production cars, it has only ever been used in Bugattis, namely the Veyron, the Chiron and their various derivatives.
As fitted to the track-only Bugatti Bolide, due to go on sale in 2024, the WR16 will produce 1578bhp.
Other configurations
And here is the first of our bonus slides.
The rotary engines mentioned previously were all of the type patented by Felix Wankel, but there is another kind which has equally spaced cylinders rotating around a stationary central crankshaft.
Iowa-based Adams-Farwell produced several cars with three- and five-rotor engines of this sort until 1912, since when no other manufacturer has followed its lead.
Chrysler, Fiat, Rover and Renault all produced gas-turbine vehicles for various purposes, but only Chrysler made one for the road.
The Chrysler Turbine (pictured) was loaned out to drivers from 1963 to 1966, but a production version didn’t follow, and Chrysler eventually gave up on turbines late in the following decade.
Motorsport applications
Among roadgoing engines, there is a mysterious gap where the flat-eight should be, but engines of this configuration have been used for motorsport.
Porsche created several flat-eight racers in the 1960s, and there were some private efforts, too, including the Glasgow-built Anderson Special, whose engine was assembled from parts of two Humber ‘fours’.
Porsche and Coventry-Climax both designed flat-16s, for Can-Am and Formula One respectively, but neither of them was used in competition.
Nor was the W9 which Renault contemplated before opting for a turbocharged V6 instead, or the extraordinary supercharged 16-cylinder air-cooled radial developed for the front-wheel-drive Trossi-Monaco (pictured) in the 1930s.
BRM developed a 3-litre H16 (essentially two 1.5-litre flat-eights, one lying on top of the other) for F1, in which it did moderately well, though it won a Grand Prix only when fitted to a Lotus and not to one of BRM’s own cars.
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