Engines worth opening the bonnet for

Most engines are not beautiful. Useful, yes. Impressive, occasionally. But beautiful? That’s a rarer thing. Plenty of engines spend their lives hidden beneath plastic covers, looking less like feats of engineering and more like the inside of a photocopier.

The great ones are different. They make you want to open the bonnet even when nothing is wrong, which is the highest compliment an engine can receive. Not to check fluids, not to diagnose a noise, just to admire the thing.

Here are a few that earned the right.

Ferrari’s Colombo V12 is one of those engines that looks exactly how people think a classic Ferrari engine should look: red cam covers, polished carburettor trumpets, neat pipework and just enough mechanical complexity to suggest very expensive consequences if you touch the wrong bit.

Its most famous visual form is probably the Testa Rossa specification, where the red-painted cylinder heads gave the car its name. Add six twin-choke Weber carburettors and you have something that looks less like an engine bay and more like an altar to controlled combustion.

There’s a reason people lean over these at shows for slightly longer than is socially normal.

The Jaguar XK engine is proof that function can look elegant without trying too hard. Twin polished cam covers, six cylinders in a long, purposeful line, and that lovely sense of balance you get from a proper straight-six. It looked right in everything from the XK120 to the E-Type, which is not a bad CV, really.

The clever bit is that it never feels decorative for the sake of it. It looks like an engine built to work, but by people who understood that a car as beautiful as a Jaguar deserved something decent under the bonnet too.

In other words, no awkward moment when you lift the lid and find a jumble of hoses spoiling the romance.

The Alfa Romeo Busso V6 might be the prettiest engine ever fitted to a relatively attainable car. That is the important bit. You didn’t need a seven-figure Ferrari or a coachbuilt unicorn to enjoy it. You could find this wonderful V6 in cars people actually bought, used, neglected, loved, cursed and then loved again because that is generally how Alfa ownership works.

The later 24-valve versions are especially glorious, with those polished intake runners sitting proudly across the top like jewellery. It doesn’t just sound good – although it very much does – it looks as if someone cared deeply about making an engine bay feel special. Which, in a world of plastic covers, feels almost heroic.

The BMW M88 is not pretty in a delicate way. It is pretty in a serious, purposeful, slightly intimidating way. Born from BMW’s M1 programme and later used in cars such as the M635 CSi and original M5, it has that magnificent straight-six layout with individual throttle bodies and a sense of engineering order that feels very BMW. Everything looks considered. Nothing appears to have wandered in by accident.

It is the opposite of flamboyant Italian engine dressing. No theatrical red paint, no jewellery-box nonsense. Just metal, symmetry and intent. Very German, then.

Ferruccio Lamborghini did not start a sports car company because he wanted to be subtle. Conveniently, the early Lamborghini V12 wasn’t subtle either.

Designed by Giotto Bizzarrini, it began life as a 3.5-litre unit for Lamborghini’s first road cars and went on, in heavily evolved form, to power generations of V12 Lamborghinis. In a Miura, with the engine mounted transversely behind the seats, it becomes even more of a visual event: twelve cylinders, carburettors, linkages and mechanical theatre packed into a space where most manufacturers would have given up and gone home.

It looks complicated, expensive and faintly unreasonable. Perfect Lamborghini, in other words.

The Bugatti Type 35’s straight-eight engine belongs to an earlier, more elegant kind of engineering. This was an engine from a time when racing machinery could still look like jewellery. Long, narrow, beautifully arranged and full of fine mechanical detail, it matched the rest of the Type 35 perfectly. Even the car’s alloy wheels and hollow front axle had that Bugatti knack of making clever engineering look graceful.

Of course, it was not just for display. The Type 35 became one of the most successful racing cars ever built, which rather helps the legend. Still, plenty of winning engines are ugly. This one had the decency to be lovely too.

The Mercedes-Benz 300SL engine is beautiful partly because it is clever in a visible way. Its straight-six was tilted over at an angle, allowing that famously low bonnet line while making room for proper breathing. Add mechanical fuel injection and you have an engine bay that feels technical, exotic and beautifully disciplined.

It is not showy like a Ferrari, nor theatrical like a Lamborghini. It has a cooler kind of beauty: precise, purposeful and faintly scientific. The sort of engine that looks as if it would quietly correct your grammar.

A beautiful engine does more than power a car. It gives you a reason to lift the bonnet when everything is working perfectly.