Transverse engine

Transverse engine /trans-vers en-jin/ noun (countable)

A transverse engine is an internal combustion engine that is mounted in a vehicle with its crankshaft oriented sideways, perpendicular to the direction of travel. This is the engineering masterstroke of turning the engine sideways to free up an astonishing amount of space for people and their luggage. It is the packaging principle that allowed for the creation of the modern small car and is the reason you no longer have to sit with your legs splayed around a giant transmission tunnel. While a few cars had tried it before, the transverse engine was perfected and popularised by Alec Issigonis in the 1959 Mini. It was a moment of such profound, game-changing logic that almost every other manufacturer on the planet was forced to copy it.

The Full Story of the Transverse Engine

For the first sixty years of the motor car, the engine was almost always mounted longitudinally, or "north-south," pointing down the length of the car. This made perfect sense for the traditional rear-wheel-drive layout, as it lined up neatly with the propshaft. It was simple, traditional, and deeply inefficient in its use of space, demanding long bonnets and leaving little room for the occupants.

A few pre-war pioneers, notably Germany's DKW, had experimented with mounting small, two-stroke engines transversely to drive the front wheels, but the idea had never caught on in the mainstream. The revolution came from Britain, and from the mind of one brilliantly stubborn engineer. In the wake of the 1956 Suez Crisis, Alec Issigonis of the British Motor Corporation was tasked with designing a tiny, frugal car. His obsession was packaging: how to fit four adults into the smallest possible footprint.

His solution was the Mini. Issigonis’s true moment of genius was not just in turning the venerable A-Series engine sideways, but in how he dealt with the gearbox. Instead of hanging it off the end of the engine, which would have made the car too wide, he ingeniously tucked it into the engine's sump, directly underneath the crankshaft. The engine and gearbox shared the same oil. This created an incredibly short, self-contained "power pack" that could be slotted into the front of the car.

The effect on the car's proportions was transformative. The entire drivetrain took up only 20% of the Mini's total length, leaving a staggering 80% of the car's footprint for the passenger cabin and a tiny boot. It was a packaging miracle that made every other small car on the market look instantly obsolete, bloated, and hopelessly old-fashioned.

The Issigonis layout became the foundation of BMC's, and later British Leyland's, entire range of front-wheel-drive family cars. While the world admired the cleverness of the principle, the gearbox-in-sump design could be problematic, with the shared oil being a poor compromise and contributing to the transmission's famous whine. The rest of the world soon followed the transverse-engine principle, but most adopted the slightly less compact but more robust layout pioneered by the Italian engineer Dante Giacosa, who placed the gearbox on the end of the engine. This became the absolute standard for front-wheel-drive cars. The initial spark of genius, however, the idea that completely redrew the map of car design, was entirely British.

For The Record

Why are engines not always mounted transversely?

In a rear-wheel-drive car, a longitudinal (north-south) engine lines up naturally with the propshaft going to the rear axle. It's the simplest and most direct layout. It is also better for the weight distribution of a large performance car and is the only way to fit very long engines, like a V8 or V12, into the engine bay.

Did the Mini's gearbox-in-sump design have any problems?

Yes. The engine and gearbox sharing the same oil was a compromise. Engine oil is not ideal for the immense pressures inside a gearbox, and tiny metal particles from the gears could contaminate the engine oil. It also gave many Minis a distinctive, high-pitched gearbox whine.

What car first used the now-standard "end-on" gearbox layout?

The 1964 Autobianchi Primula, designed by the great Italian engineer Dante Giacosa. He would later use the same refined layout on the hugely influential Fiat 128. This layout, with the engine and gearbox side-by-side driving the front wheels, is the blueprint for almost all modern front-wheel-drive cars.

Can a mid-engined car have a transverse engine?

Yes, many do. Placing the engine and gearbox unit sideways just behind the driver is a very compact and efficient way to build a mid-engined car. Many affordable mid-engined sports cars, like the Toyota MR2, Fiat X1/9, and Lotus Elise, have used this layout.

Was Alec Issigonis a fan of cars?

Famously, no. He was a pure, unsentimental engineer who saw cars as a functional solution to a transport problem. He reportedly disliked driving for pleasure and was dismissive of the sporty Cooper versions of his Mini, viewing them as a frivolous corruption of his minimalist, utilitarian design.