Don’t like the sound BMW’s M3 convertible makes? Why not option for a Doppelturbo 335i - just as fast, yet more sonorous.

ATT Autotechnik’s fabulously named Doppelturbo kit is one of those performance solutions to a problem we’re not sure really exists – making 335i convertibles into M3 challengers.

It sounds like an odd idea, yet when you've become accustomed to the whims, and sometimes odd product planning, of Germany's tuning fraternity, building an M3-chaser from 335 bits is not such a far-fetched idea.

Doppelturbo - double the fun?

As it stands though, if you believe V8s are sacrilege when shoehorned into a 3 Series body shell, you’ll probably be suitably impressed with ATT’s latest work.

The German tuner has liberally recalibrated the eminently tuneable 3l twin-turbo in-lines six’s ECU module.

This boosts the N54 engine’s power by 37kW to 262kW, whilst peak rotational force swells by 126 units, from 400- to 526Nm.

Power output might be well shy of the M3 V8’s 309kW rating, yet the ATT Doppelturbo conversion brings 126Nm more torque to the game.

In cut and thrust daily driving, we reckon the Doppelturbo should have an edge.


Stock 335 brake rotors appear a trifle undersized behind those wheels...

M3 trinkets

Beyond the engine conversion ATT will embellish your 335i convertible with some faux M3 optics, including the characteristic aero duct cut-out just aft of the front wheelarches.

Rolling in the Doppelturbo’s wheelarches are multi-spoke 20-inch wheels (which seem like something Alpina would have fitted). The standard brakes look as if they’re drowning in full view behind those huge mags though.

If you make your way to Rastatt in Germany, ATT will even finish your 335i Doppelturbo in a range of custom colours.

So, if you simply must have your convertible 3 Series performance delivered with strikingly capable (yet silky-smooth) in-line six power, the ATT Doppelturbo is just for you.

Or you could just do the sensible thing and buy an M3 convertible…