Detroit 2010: BMW Z4 sDrive35is

BMW has taken the wraps off this new range-topping Z4 sDrive35is at the Detroit Motor Show. But while it's not called the Z4M, the stats prove otherwise.

BMW has already stated that it’s not going to build an M version of its latest Z4. But while the firm is keen the ensure its latest roadster is seen as a cleaner, more sensible everyday car, that hasn’t stopped the M division tickling a few extra horses out of the top spec Z.

So what makes the sDrive35is tick?
Well, the hottest Z4 of the current generation is based on the sDrive35i, complete with 3.0-litre twin turbo six cylinder engine. But on the is it gets a revised, freer flowing air intake, a higher boost pressure for the two turbos and a new mapping for the ECU.

What about the power?
This means that the power has gone up to 340hp and torque has swelled to 450Nm. What’s more there’s a new overboost function too, which delivers an extra 50Nm for short bursts. So, coupled to the launch control this means 0-62mph takes 4.8 seconds while the top speed remains limited to 155mph.

Anything else of note?
The Z4 sDrive35is is only available with the seven speed DCT transmission which has been recalibrated for even faster shifts, and the exhaust now has flaps in it which open to make the engine sound more meaty. An M Sports package is included too, which includes 10mm lower suspension and a new aerodynamic bodykit.

How does it compare with the old Z4M?
The previous range-topping Z4M had the M3’s 3.2-litre 343hp engine and could manage 0-62mph in 5.1 seconds, 23.3mpg and 292g/km of CO2. The new un-M Z4 is faster off the mark, yet manages 31.4mpg and 210g/km.

But most telling is that the new Z4 has the extra tractability of 450Nm – the old car had to make do with 365Nm – making it super-easy to drive and even faster in the real world despite weighing 85kg more. is IS the new M.