As hard as it might be to believe, we might have a bottle of spiced rum to thank for one of the greatest BMW M cars ever built.

Back in 2009, a group of engineers at BMW's M division set to work on a secret weekend project, and it seems on at least one occasion, they had a bottle of Pyrat nearby - enough to give the project its official codename of 'Pyrat'. 

In fact, if you look hard enough at certain parts stickers on the BMW 1M Coupe today - like the wheel-housing liners - you’ll actually find the word "Pyrat" printed on them.

But that's only the start of this mad story.

How the 1M Coupe came about

We currently have a 2012 BMW 135i M Sport coupe online in our Canberra Premium and Prestige auction, equipped with a 3.0-litre turbocharged inline-6 and rear-wheel drive.

Funnily enough, that’s exactly where the M upgrades were supposed to stop for the 1 Series. 

Corporate bosses originally intended for the standard 135i to be the official top-tier M version, and with 400 Nm of torque on tap from just 1,200 rpm, it certainly had the credentials.

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But a few rogue engineers weren't ready to settle.

BMW wasn't exactly handing out bags of cash for fun "what-if" projects right after the Global Financial Crisis, so the team decided to tinker with the 135i Coupe in their own time. 

Over the course of a year, they grabbed the twin-turbo engine from a Z4 and violently wedged the suspension, brakes, rear axle, and differential from an E92 M3 Competition into its tiny chassis. This swelled the front track by a massive 71 mm, forcing them to aggressively stretch the bodywork just to cover the wheels.

The BMW 1M Coupe, in its hero colour of Valencia Orange - possibly also rum-inspired. Photo: BMW Group.

When the Head of M, Dr Kay Segler, returned from a two-week trip, the engineers wheeled out the prototype. It could have gone terribly - like a toddler showing their parents the mural they’d just drawn in permanent marker on the living room wall.

Instead, Dr Segler took one look and championed the project. 

"We need to build this car," he reportedly said when he saw the completed car for the first time.

How it became a legend

BMW announced the project to the world in 2010, but the constraints were brutal. 

Because they were virtually out of time and budget before the next-gen 1-Series arrived, the engineers had to make a few sacrifices. For instance, they originally wanted a carbon-fibre roof and functional front fender vents, but the stamping moulds couldn't be perfected in time, leaving us with aesthetic creases instead.

The plan was to use cheap halogen headlights to keep the base price under 50,000 Euros, but the 1M's ridiculously wide front guards soon blew a hole in that. The parking lights sat too far inward to comply with Germany's design regulations, so BMW was forced to make the more expensive xenon "Angel Eye" headlights standard, pushing up the price.

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When it finally went on sale in May 2011 at $99,900 AUD, it wasn't exactly an instant hit either. M purists whined that it wasn't a "real" M car because it used a borrowed turbocharged engine, rather than its own naturally-aspirated one. 

Then they drove it. With 250 kW, an overboost function pumping out 500 Nm, and a 0-100 km/h time of 4.9 seconds, it was seriously rapid. Or as Dr Segler put it: "The 1M is basically a truncated M3 Competition Package with a manual."

BMW initially planned a tiny run of 2,700 units worldwide. But demand was so hysterical they ended up building 6,309. Only about 300 made it to Australia, and they're still aggressively holding their value today, commanding between $75,000 and $95,000.

Our car

Our 135i auction car might not wear the official 1M badge, but make no mistake: it shares the same DNA, the same short-wheelbase chassis, and is only mildly less ludicrous. 

It’s a 2012 model in clean, tidy condition, showing 183,668 km on the clock with a partial logbook service history. 

All it’s missing is a few shots of Pyrat.