BMW’s M division is famous for its secret prototypes – over the years, there’s been an E34 M5 cabriolet, an E92 M3 pick-up, and perhaps most famously, the stillborn M8 with its mighty V12. In XP1, Jethro Noble gave us the story of the E36 M3 Compact (that went on to father the Z3 M Coupe), but arguably the one that showed the most intent was the E46 M3 Touring.

The clue lies in the striking Chrome Shadow paint. Fearsomely expensive to produce, the car first had to be sprayed a high-gloss black before being overlaid with silver. M GmbH reserved this distinctive finish for the M3 Coupe, M3 GTR, M3 CSL, and later E60 M5 concept cars during their respective motor show debuts. The M division clearly had significant ambitions for this prototype – every other concept finished in Chrome Shadow went into production.

It certainly looks the part, doesn’t it? All the E46 hallmarks are there – from the powerdome bonnet, to the gills aft of the front arches, the widened track, and the signature four exhaust pipes. Why the concept never went into production remains a tightly guarded secret at BMW M. Accommodating the E46’s unique rear axle without severely compromising the Touring’s load space is one touted stumbling block. The cost of the required strengthening to the Touring bodyshell is another. Given how notoriously fragile the coupe’s rear subframe is, one can only imagine how susceptible the Touring would be...

Perhaps the inevitable weight penalty would prove too much for the 106bhp/litre, high-revving, naturally aspirated straight-six to overcome – especially given the torque deficit when compared to forced induction rivals from Audi (RS4 Avant – twin-turbocharged V6, 325lb-ft) or Mercedes-Benz (C32 AMG Estate – supercharged V6, 332lb-ft), which could easily absorb the additional kilos in terms of straight-line performance. The M3’s S54 mustered 262lb-ft in comparison, delivered at a lofty 4,900rpm. Not a problem in the coupe, but a potential concern in a heavier Touring variant.

You might also like:

www.rushmagazine.co.uk

BMW has finally relented to demands and given us an M3 Touring. Craig Toone gets behind the wheel and puts the car to the test. Will the car live up to the hopes and dreams of M enthusiasts?

www.rushmagazine.co.uk

A super saloon should look like Clark Kent, yet be powered like Superman. For many, the definition of the breed is the E39 generation BMW M5. Time for Craig to meet his superhero.

Another possible reason is the significant production costs and engineering expertise required to seamlessly integrate the Touring’s rear doors with the significantly flared arches. Given Audi had already achieved this with the RS4, it seems unlikely that M GmbH would have allowed Ingolstadt to maintain an edge by employing a less refined solution. Perhaps BMW bosses were concerned the Touring (and the inevitable clamour for a saloon to follow) might cannibalise sales from the M5 – even if history has proven otherwise.

Whatever the ultimate reason, the E46 M3 Touring never had its moment under the motor show lights and was only revealed to the public sixteen years after its conception. While there have been many more exciting, fully functioning M prototypes since – including the M5 CSL and M2 GTS – none have captured the imagination like the E46 M3 Touring. Now, with the G81, BMW M has finally made it a production reality.