Engine layout used to tell you what kind of car you were looking at. Four cylinders meant economy, six meant family, eight meant power or work. I counted what's actually recorded across our engine data.
| Engine layout | Records |
|---|---|
| 4-cylinder | |
| V6 | |
| V8 | |
| Hybrid | |
| Electric | |
| 5-cylinder |
The four-cylinder leads, but the more telling comparison is against what it replaced. Four-cylinders and V6s are now within 11% of each other — in a market where the V6 was once the default for anything larger than a compact.
The four-cylinder won by getting a turbo
This isn't a story about buyers choosing economy. It's a story about a four-cylinder becoming capable of jobs it couldn't previously do.
A turbocharged 2.0-litre now produces what a naturally aspirated 3.5-litre V6 made twenty years ago. Once that was true, the V6 had no argument left — it was heavier, thirstier on the test cycle, and cost more to build. Manufacturers replaced it almost everywhere: midsize saloons, crossovers, even full-size SUVs.
We watched the same thing from the other direction when we found the average engine losing half a litre and most of a cylinder over thirty years. This table is what that looks like in the parts bin.
The V8 didn't die, it retreated
4,665 records is a lot for an engine everyone describes as extinct. What changed is where it lives.
V8s used to appear in family saloons, estates and mid-range SUVs. Now they're concentrated at two ends: full-size trucks that genuinely need the torque, and performance cars where the sound is part of the product. The middle ground — a V8 in an ordinary car — is what disappeared.
What this changes when buying used
Engine choice within one model matters more than it used to. The same body might have come with a naturally aspirated four, a turbo four and a V6, and those are three different cars in terms of running cost, reliability profile and what fails. The badge on the back tells you almost nothing.
Turbo fours are less forgiving. A small turbocharged engine doing a big engine's work runs at higher loads and pressures. Done well, it lasts. Neglected, it doesn't — and turbochargers, high-pressure fuel pumps and injectors are expensive. On a used turbo car, documented oil-change history is worth more than 20,000 fewer miles on the odometer.
The old V6 is quietly a good buy. Naturally aspirated V6s from the 2005–2015 era are among the least stressed engines ever mass-produced — no turbo, no direct injection carbon issues, and a design that had been iterated for decades. They cost more in fuel and less in surprises.
How to check what's actually in the car
Pull the original window sticker by VIN. It lists the exact engine the car left the factory with, which a spec sheet won't tell you and a seller may not know. That's the window sticker lookup, and it works on cars whose paperwork vanished years ago.
Then check what's open on that combination — turbo and direct-injection systems have generated some of the largest recall campaigns of the last decade, and they're exactly the ones a third owner never hears about. A free VIN check shows them.
Frequently asked questions
What is the most common engine layout now?
The four-cylinder, with 6,877 records in our data against 6,170 V6s and 4,665 V8s. Hybrids account for 1,406 and electrics 540.
Why did four-cylinder engines replace V6s?
Turbocharging. A turbo 2.0-litre now makes what a naturally aspirated 3.5-litre V6 made two decades ago, which removed the V6's advantage while it remained heavier and costlier to build.
Are V8 engines disappearing?
They've retreated rather than died. V8s remain common in full-size trucks and performance cars but have largely vanished from ordinary saloons, estates and mid-range SUVs.
Is a turbo four-cylinder reliable used?
It's less forgiving than a naturally aspirated engine. Higher loads and pressures mean oil quality matters more, and turbochargers, high-pressure fuel pumps and injectors are costly to replace. Documented service history counts for more than a lower odometer reading.
Denis Kataev is a serial solopreneur and the founder of ForCar. With 15+ years in software engineering and 10 years in SEO, he builds data-driven products end to end — backed by a sharp eye for design. At ForCar he mines proprietary vehicle datasets, turning raw numbers into buying advice you can actually trust.
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