The first
1978 · Saab 99 Turbo
The first mass-market production turbocharged petrol car was the Saab 99 Turbo, launched in 1978 with a 2.0-litre four-cylinder making 145 bhp. The technology had existed for decades — Chevrolet had built turbocharged Corvairs in the early 1960s and Porsche launched the 911 Turbo in 1974 — but the 99 was the first time a turbocharged engine appeared in a car aimed at family buyers rather than wealthy enthusiasts.
It was, by modern standards, awful. Turbo lag was measured in full seconds. The wastegate was crude, the cooling was marginal, and the engine had a tendency to detonate spectacularly if you used cheap petrol. The redeeming feature was that, when the boost finally arrived at around 3,500 rpm, the 99 was genuinely fast — quicker than a Volvo 244 GLE, quicker than a BMW 320, quicker than almost anything on family dealer forecourts.
Saab spent the next decade refining it, and by the late 1980s the 9000 Turbo was a cult car among journalists. But turbocharging stayed niche through the 1980s and most of the 1990s. The default fast saloon engine was a normally-aspirated straight-six (BMW M3, Mercedes 190E 2.5-16) or a screaming four-pot (Honda Type R). Turbos were for diesels and the lunatic fringe.
What's worth understanding is why turbos worked on diesels but not yet on petrols. A diesel engine, with its high compression ratio and lean-burn character, was ideal for forced induction — the increased airflow and pressure improved efficiency rather than threatening detonation. A petrol engine, especially with 1980s-era electronics, struggled to manage the higher cylinder pressures. Detonation was the constant enemy. The result was that 1980s turbocharged petrol engines either had to run very low compression (8:1 or lower, ruining off-boost economy) or accept a knock-prone, fuel-thirsty character. Diesels had no such constraint.
The lost decade
Through the 1990s, turbocharging on petrol cars was almost exclusively the preserve of Japanese performance specials (Skyline GT-R, WRX, Lancer Evo) and a thin slice of European hot hatches (Saab, the 1990s Renault 5 GT Turbo, the Lancia Delta Integrale). The wider market saw turbos as a reliability liability — and they often were. Early Mitsubishi turbos blew at 60,000 miles. Saab 9-3s ate turbo seals. The mid-1990s Renault Mégane Mk1 had a 2.0 16v in it that didn't need turbocharging and was the better for it.
The reason mass-market petrol stayed naturally aspirated was simple: at the engine sizes most people bought (1.4 to 2.0 litres), atmospheric induction made adequate power, was cheap to build, was easy to service, and lasted 150,000 miles without drama. The case for adding a turbo wasn't there.
That changed in the 2000s, for two reasons that had nothing to do with performance: emissions regulation and fuel economy.
The version that made it stick
2003 · Volkswagen Golf Mk5 GTI
The Mk5 Golf GTI launched in 2004 with a 2.0-litre turbocharged direct-injection engine — VW's first volume application of TSI/TFSI technology — making 197 bhp. Crucially it produced the same peak torque (207 lb-ft) as a 3.0-litre naturally aspirated six, available from 1,800 rpm.
That was the breakthrough. For thirty years the GTI had been a normally-aspirated 1.8 or 2.0 making peak torque at 4,500 rpm. The Mk5 redefined the recipe: same drivability, half the displacement, same fuel consumption on a steady cruise, and 50% more torque when you pressed the throttle. By the time the Mk6 GTI arrived in 2008, every European hot hatch was turbocharged. The naturally-aspirated hot hatch was effectively dead.
The technology that made the Mk5 GTI work wasn't just the turbocharger. It was the pairing of turbocharging with direct injection. Direct injection allowed higher compression ratios (10.5:1 on the Mk5 GTI engine, where 1990s turbos managed 8.5:1 at most) because the cooling effect of in-cylinder fuel evaporation suppressed detonation. That meant the engine made good off-boost economy and good on-boost power — the holy grail that 1980s engineers couldn't reach.
The Mk5 GTI didn't kill the naturally-aspirated engine. It just proved you didn't need one.
The downsizing wave
What VW had proved on a hot hatch, Ford applied to a supermini. The 1.0-litre EcoBoost Fiesta (2012) replaced the old 1.4-litre Duratec with a turbocharged three-cylinder making 99 bhp at 6,000 rpm and — more importantly — 125 lb-ft from 1,400 rpm. WLTP combined economy on the 99 bhp Fiesta was 58.9 mpg. Not far off the diesel.
That was the template every manufacturer copied between 2012 and 2018. Three-cylinder 1.0-litre turbos took over the supermini segment (Polo, Corsa, Sandero, Yaris, 208). 1.5-litre turbos took over family hatches and saloons (Focus, Astra, Civic, Mégane). The 2.0-litre turbo became the default executive car engine. Mercedes-Benz and BMW dropped naturally-aspirated sixes by 2014. Audi switched the A6 from a 3.0 V6 to a 2.0 turbo on the volume model.
By 2018 the only mass-market petrol cars on UK sale without forced induction were the cheapest Dacia, the smallest Toyota Aygo, and the bottom of the Hyundai i10 range. Everything else had a turbo.
The unintended consequences
Mass turbocharging worked on paper but had two significant side effects on the road.
Reliability. 1.0-litre turbos working hard to do 1.6-litre work generate a lot of heat in a small space, and the early downsized engines (the Ford 1.0 EcoBoost in particular) had wet timing belts that needed expensive proactive replacement, plus a tendency to crack heads when the cooling system aged. By 2018 a five-year-old EcoBoost Fiesta had a higher service-to-value ratio than a 1990s Mondeo with twice the mileage.
The Ford 1.0 EcoBoost specifically became a cautionary tale. The wet timing belt — designed to reduce friction by running in oil — had a 100,000-mile service interval that proved optimistic. Belts could fail at 60,000 miles, often catastrophically (valves hit pistons, engine destroyed). Ford issued partial recalls and extended warranty programmes through 2020. The volume of failures created a thriving aftermarket: by 2024, replacement EcoBoost engines were advertised on every UK auto-trade site, often at £2,500 fitted — on cars worth £4,000.
Real-world economy. WLTP and NEDC tests measured fuel use at low loads, where small turbos look brilliant. In the real world, where drivers actually want to overtake or merge, the turbo is on boost more often than the test cycle assumes, and a 1.0-litre downsized turbo doing the work of a 1.6 actually returns worse fuel economy than the old 1.6 at motorway speeds. Real-world MPG figures from Honest John and Parkers consistently showed downsized turbos missing their official figures by 15-25%.
The "downsizing gap" became a known phenomenon by 2017. The European Commission's own real-world emissions testing found that on average across mass-market petrol cars, real-world CO2 emissions were 42% higher than NEDC quoted figures. WLTP narrowed the gap somewhat but didn't eliminate it.
The reversal
By 2020, manufacturers were quietly upsizing again. The current 1.5-litre Volkswagen TSI replaced the old 1.0 and 1.2 across most of the range. BMW's three-cylinder 1.5 turbo in the 1 Series and 2 Series Active Tourer was replaced by a 2.0 four-cylinder for the 2024 facelift. Honda's 1.0 turbo in the Civic was replaced by a 1.5 hybrid. The downsizing wave receded.
What's stuck is the turbo itself. As of 2026, naturally aspirated petrol cars are rare in the UK new-car market — the Suzuki Swift, the Mazda MX-5, the high-revving Honda Civic Type R, a handful of luxury V12s. Everything else has at least one turbocharger.
The interesting hybrid case is the mild hybrid integration. Many modern small-displacement petrol engines now run a 48V starter-generator that provides torque assist during turbo lag, masking the lag entirely. The current Audi A4 1.5 TFSI evo, the Mercedes A-Class A180, and the Volvo XC40 all use this approach. The result is that a 1.5-litre four-cylinder turbo with 48V assist feels, from the driver's seat, like a 2.5-litre normally-aspirated six — instant torque from idle, no boost-build delay. The hybrid hardware solved what twenty-five years of turbocharger development couldn't quite solve on its own.
The afterlife
The Saab 99 Turbo's marketing line in 1978 was "the most exciting performance car since…the last most exciting performance car." Forty-eight years later the answer is: every Ford Fiesta, every VW Golf, every Mercedes A-Class. The turbo won. It just took a long time, and it didn't win the war it set out to fight.
What the turbo originally promised was high specific output — power-per-litre figures previously only available on race-bred engines. What it actually delivered, in the long run, was a way for emissions regulators to mandate smaller engines without forcing manufacturers to accept a power deficit. The performance use case became the rounding error; the regulatory use case became the reason every car has a turbo.
That's the unspoken story of forced induction. It was developed as a performance technology in the 1970s, struggled to find a mass market for thirty years, and was finally adopted at scale not because anyone wanted faster cars but because regulators wanted smaller engines. The turbo became universal at the moment it stopped being a performance feature.
The Suzuki Swift, the Mazda MX-5, and the Honda Civic Type R — the three holdouts on naturally-aspirated petrol — survive partly because their buyers explicitly want the linear power delivery and high-rev character that turbos still struggle to fully replicate. They're niche cars now. The mainstream chose efficiency over involvement, and the turbo was the technology that delivered it. Forty-eight years after the Saab 99 Turbo, that's the actual legacy.