BMW Z4 20i 2011 review

There's always a bit left over when you divide six by four. For BMW's Z4 20i what's left is a lighter, nimbler roadster that uses 20 per cent less fuel than its six-cylinder predecessor. It still hammers harder than a nailgun and its pose value is up there with Miranda Kerr in a Victoria's Secret outfit.

Value

The Beatles reckoned money can't buy you love. Z4 buyers will disagree. Owners will adore it and others will lust after it, so the $77,000 starting price is pretty much irrelevant.

It is housed in a hardtop roadster that spins heads as quickly as the twin-scroll turbo spools up. Spend another $12,500 and the same engine is fettled to produce 180kW/350Nm in the Z4 sDrive 28i.

Technology

Brake energy regeneration is standard on most European cars these days - it recharges the high-output battery and lets it deal with the on-demand ancillary systems rather than have them suck power and petrol from the engine. It is the engine that does the job, though.

A decent run in the base Z4 saw it use just 8.0 litres/100km. Sporty cars - the 20i hits 100km/h from rest in 6.9 seconds - aren't meant to be that efficient, especially not when they're being pushed. Push the button to drop the top and cruise and the fuel figure will fall accordingly.

Styling

The original Z3 was derided for its soft looks. The same can't be said for the Z4. It's a classic roadster style with a bonnet you can land a small plane on arching up to a curved roof and stumpy tail. BMW says there's 180 litres of space in the boot, but you'll be buying bags from Ikea to fit - flat-pack is the name of the game.

A smarter option is to lift the plastic cowl in the rear and not drop the top until you reach your destination. That then gives 310 litres of much more practical space. Put the bags in your room and then you can go topless.

Safety

The expected safety systems are all there ... and then there's the options list for those who want the best of everything. That runs from adaptive headlights with a high-beam assist that automatically dims the light for approaching vehicles to adaptive cruise control, parking sensors and emergency phone calls.

The basic structure is a five-star vehicle - the roof is effectively a rollover hoop and there are pop-up bars behind the seats if things go pear-shaped with the lid down, while four airbags cushion the blow.

Driving

City running in the Z4 shows a lot of work has gone into keeping the interior quiet. There's a mild mechanical turbine whine from standstill but it is all pretty muted until you stand on the go-pedal. Then it snarls and gets down to business. The manual gearbox is notchier than most Beemers but the throw is precise.

Given how good the eight-speed auto is, though, I'd seriously consider spending another $3500 to have it. Blaspemy? Not in this day of computerised nano-second gearchanges and steering wheel paddle-shifts. The button next to the gearshift has Comfort, Sport and Sport+ settings for the suspension, steering, throttle response etc.

Keep away from Sport+ - it loosens the stability control and makes the rear end twitchier than a bridgroom on the wedding day, despite the claimed 52/48 weight distribution. Sport is the sweet spot for the Z4 and coupled with the spot-on steering makes this an engaging drive rather than a too-entertaining one.