BMW’s just launched Z4 sDrive 35is convertible is a hard-edged, no-compromise machine for the keen driver. The fact that our review car was hot red in colour made it all the more exciting.

Power comes from a 250 kilowatt twin-turbo engine, which is significantly up from 224 kW on the standard Z4 sDrive 35i. (Note that BMW continues its new tradition of using odd model names - the ‘i’ means a 224 kW engine, the ‘is’ the 250 kW unit.)

The engine in this latest BMW Z4 is the last of the famed twin-turbo 3.0-litre straight-six powerplants that have delighted us for a number of years. BMW is switching to a single-turbo engine with twin scrolls that it feels provides equal performance to the twin-turbo unit. We have been told the single turbo is cheaper to produce but BMW will neither confirm nor deny that fact.

The engine normally produces up to 450 Nm of torque which is already a big number for a 3.0-litre engine, albeit a turbocharged one. But an additional 50 Newton metres is offered by way of a short period of overboost from the turbos, something that will really appeal to those who want to use their Z4 35is on track days. In fact that 500 Newton metres is just the thing for getting past slow cars in the shortest possible time in road driving.

Changes to the bodywork are minimal and consist of an aerodynamic splitter under the front of the car. There are new designs of alloy wheels, with a diameter of 18 inches as standard and the option of 19-inch units.

Adaptive suspension is part of the M Sport package and we were impressed by the way it gripped the road relentlessly after turning in sharply. Weight distribution has long been a feature of all BMWs and this is even more obvious in the low-slung Z4 roadster. Throttle control is simple and prompt and the car is more than willing to change direction mid corner. This is certainly the sort of machine you will love to get out on your favourite stretch of road very early in the morning.

BMW’s Z4 not only grips the road with a great deal of tenacity, but also provides better than average comfort for a car in this class. However, big bumps can catch it out and send a harsh crashing through the body.

The twin bucket seats provide good lateral support when the car is pushed hard, yet aren’t overly difficult to get in and out of. The styling of the cabin, particularly the dashboard area with its large easy to read dials, is excellent. It goes without saying that the quality of materials and the overall fit and finish are immaculate.

Stowage space in the cabin isn’t particularly good, just a couple of skinny pockets on the doors and a centre console that’s so shallow that it’s all but unusable. However this sort of thing is perfectly acceptable in a sportscar and some feel it adds to the character.

The ride height of the Z4 35is is lower than that of the standard model by 10 millimetres, which further enhances the already excellent road grip, but it caused a gentle scraping on a couple of marginal gutters we encountered during our road test program on the Gold Coast.

The twin-turbo BMW engine sounds simply superb when it’s worked hard, it has a deep guttural note that will bring a smile to your face. However, while the quality of the sound is great it’s lacking in overall volume. Those aforementioned track-day guys might like to have a talk to an exhaust system specialist if they want to maximise their driving pleasure.

Near instantaneous gearchanges in the seven-speed double-clutch automatic add to the driving pleasure as they help the car retain speed between shifts. The automatic blipping of the throttle is yet another feature of the BMW Z4 35is that will bring a smile to the face of those who really love their driving.

The price of the new BMW sDrive 35is is a reasonable $129,990 plus on-road charges. BMW Australia sees this model as challenging Porsche Boxster, Audi TT and Mercedes SLK and given the performance of this latest model the guys at BMW seem sure to grab a big share of the market.

2010 BMW Z4

MODEL RANGE
Z4 sDrive 23i 2.5-litre two-door convertible: $86,200 (manual), $89,500 (automatic)
Z4 sDrive 30i 3.0-litre two-door convertible: $98,100 (manual), $101,400 (automatic)
Z4 sDrive 35i 3.0-litre two-door convertible: $120,400 (manual), $116,900 (automatic)
Z4 sDrive 35is 3.0-litre two-door convertible: $129,900 (automatic)

FEATURES
ABS Brakes: Standard in all models
Automatic Transmission: Standard in 35is, optional in other models
Cruise Control: Standard in all models
Dual Front Airbags: Standard in all models
Front Side Airbags: Standard in all models
Electronic Stability Program: Standard in all models
Rear Parking Sensors: Standard in all models
Reversing Camera: Not offered
USB/Auxiliary Audio Inputs: Standard in all models
Satellite Navigation: Optional in 23i, standard in all other models
Bluetooth: Standard in all models
Steering Wheel Mounted Controls: Standard in all models

SPECIFICATIONS (BMW Z4 sDrive 35is 3.0-litre two-door convertible)

ENGINE:
Engine Capacity: 2.979 litres
Configuration: Six cylinders in line
Head Design: DOHC, four valves per cylinder
Compression Ratio: 10.2:1
Bore/Stroke: 89.6 mm x 84.0 mm
Maximum Power: 250 kW @ 5900 rpm
Maximum Torque: 450 Nm @ 1500-4500 rpm

DRIVELINE:
Driven Wheels: Rear
Manual Transmission: Not offered in 35is
Automatic Transmission: Seven-speed
Final Drive Ratio: 2.56:1

DIMENSIONS, WEIGHT AND CAPACITIES:
Length: 4239 mm
Wheelbase: 2469 mm
Width: 1790 mm
Height: 1284 mm
Turning Circle: N/A
Kerb Mass: 1525 kg
Fuel Tank Capacity: 55 litres
Towing Ability: Not recommended for towing

SUSPENSION AND BRAKES:
Front Suspension: Adaptive M suspension
Rear Suspension: Adaptive M suspension
Front Brakes: Ventilated disc
Rear Brakes: Ventilated disc

PERFORMANCE:
0-100 km/h Acceleration: 4.8 seconds

FUEL CONSUMPTION:
Type: Petrol 98RON
Combined Cycle (ADR 81/02): 9.0L/100km

GREEN VEHICLE GUIDE RATINGS:
Greenhouse Rating: 7/10
Air Pollution Rating: 6.5/10

STANDARD WARRANTY:
Three years/unlimited km