BMW Z4M: six goes into four

Newswheel staff :: 25 October 2005 :: Filed under Roadster, BMW, BMW Z4, BMW Z4M, Europe & UK, US

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Legendary straight-six for drop-top sportster

BMW’s M division has been working on a variant of the Z4 roadster. Of course, that’s the worst kept secret since a certain TV-based ginger whinger appeared on our screens one day with an extremely startled expression. But forget Anne Robinson’s drum-tight face lift, because BMW has released the first pictures and details of the new Z4M. The Bavarian outfit has also divulged deets on a new range of engines and transmissions for the rest of the Z4 line up.

The ultimate driving machine? (click for high res image)

As expected, BMW has dropped in the S54 straight-six from the existing E46-generation M3 coupe. Power and torque outputs appear to be carried over untouched at 338bhp and 269lb/ft at 7,900rpm and 4,900 rpm respectively. That, of course, translates into one of the most efficient naturally-aspirated engines in the world with a specific output of 106bhp per-litre.

As well as that fabulous engine, the Z4M also gets the M3’s six speed manual box, but the with the final drive ratio lowered to 3.62:1 for even better drivetrain response.

The Z4M boasts a Boxster S spanking 241bhp per tonne power to weight ratio

While the quoted performance numbers are impressive with the 0-62mph sprint dispatched in five seconds flat, we fancy the driving experience will be even more extreme. After all, at 1,420kg the Z4M is over 100kg lighter than the M3. The resulting 241bhp per tonne power to weight ratio is well into Porsche 911 Carrera S territory. Top speed is a computer limited 155mph.

Chassis upgrades include the usual chop and drop routine, with the car losing 10mm in ride height all round. However, an increase in wheelbase by 2mm suggests that the suspension has been thoroughly worked over. The subtle body mods are limited to new front and rear bumpers, refreshed tailights and the M division’s signature quad exhausts.
 

The best news? The return to hydraulic power steering assistance

But while an awesome straight-six mill and a retuned chassis are reason enough for rejoicing, we reckon it’s the detail specs that are most promising. First, the Z4M will likely deliver the ultimate in tail-sliding, sideways driving precision thanks to the fitment of the M3’s awesome variable M Differential. But perhaps even more promising is the revelation that BMW has returned to hydraulic power assistance for the Z4M in search of that increasingly illusive of dynamic traits, steering feel. The Z4 has always been a massively competent car crying out for a little more driver interaction. And all the evidence suggests the Z4M will deliver just that.

The rest of the Z4 range gets a polish, too

BMW has also announced a complete overhaul of the remainder of the straight-six powered Z4 range. The new 3.0si receives BMW’s fantastic ultra lightweight magnesium alloy six in 265bhp trim and enough performance (0-62mph in 5.7 seconds) to give a Porsche Boxster S a scare. Finally, BMW has a dded a pair of new 2.5-litre powered Z4s with outputs of 177bhp and 215bhp respectively. All three models come standard with six-speed manual gearboxes.

The Z4M will be unveiled at the Detroit motor show in Jnauary. Sales start next spring but pricing info has yet to be released.