2007 BMW Z4 3.0si road test

Sun shines upon man and roadster

By Rob Rothwell

Probabilities can mislead. For example, the probability of enjoying a week of solid sunshine in Canada's rain forest concurrent with testing a roadster is as unlikely as being struck by a meteorite while hundreds of feet below the ground in a subterranean vault- but I guess it could happen. And so it did for me recently. The meteorite in question- a 2007 BMW Z4 3.0si.

The Z4 has that little something that brings back memories of roadsters of yesteryear.

Distinctly BMW- distinctly roadster

There's something quite igniting in the Z4's aggressive styling, which burns its way into one's senses. Perhaps there's more to Bangle's "Flame Surface," design philosophy than I've formerly credited him with. Beyond the Z4's dramatic lines, I revel like a child in the way the car imparts a feel of nostalgia when seated behind its wheel. Whether that's intentional or not I can't definitively say, but a sense of occupying the cockpit of an open roadster from the 1950s and 60s germinates in me every time I take a seat in the Z4.

Contributing to the retro-response is the Z4's clean, simplistic instrument panel, its long rounded hood and its low-slung windscreen. But most of all, seating positioned just ahead of the rear axle is what delivers the traditional "roadster" character that is missing in many modern convertible sports cars. Adding to the Z4's true-roadster'ism is its naturally aspirated, inline six-cylinder mill that dispenses an auditory barrage full of credibility and heritage.

3.0si power and performance

The "si" designation represents the install of BMW's latest I-6: the 3.0-litre N52, featuring a lightweight magnesium block and BMW's latest Valvetronic, variable valve timing technology. Not only is this engine considerably more powerful than the standard Z4 3.0-litre mill, it provides much better mid-range response while improving cornering by lightening the load bore by the front wheels.

The N52 generates 255-horsepower @ 6,600-rpm and 220 pound-feet of torque @ just 2,750-rpm. That's 40 horsepower and 35 pounds of torque more than dispensed by the standard 3.0-litre engine; and what a difference it makes. Having driven the less powerful Z4 and been quite content with its gusto, I was absolutely elated burying my foot into the 3.0si. This engine pulls ferociously- especially on the highway where passing power is frankly startling.

The engine displays strength throughout its broad powerband however north of 4,500-rpm is where the after-burner effect of BMW's Valvetronic technology is most felt. Keeping the engine above this threshold produces formidable performance, not to mention an exhaust note capable of terrifying owners of domestic muscle cars. This sort of motoring, while something the Z4 3.0si is engineered to excel at, isn't appropriate on anything less than a closed track. Typical automotive operation finds the Z4 3.0si well suited to city or highway demands whilst nary breaking a sweat to keep-up or pass.

It likes to be thrown into curves but also feels at ease cruising down the boulevard.

Happily, the new powerplant is packaged with a six-speed manual gearbox or an optional six-speed, paddle-shift-equipped autobox; both connected to the rear wheels. A sigh of delight was heard for miles as I climbed aboard my tester and allowed my hand to fall upon its manual stick. That may read like cheap trash but it's figuratively true. There's not much sweeter in the auto industry than BMW's six-to-six, that's six cylinders to six cogs.

The manual stick's throws are short. Each gate is clearly defined with movement that is precise, notchy and sufficiently resistive, making the Z4 a treat to administer for the purists who disdain manual-mode automatics, to which, count me in.

Handling itself like a pro

Even with its stability and traction control programs in full operation, the Z4 3.0si allows plenty of leniency before intruding on the fun, and when it does, it does so discreetly. Electronic parenting of this sort is an important safety feature in a vehicle with this much power and allure. For the highly skilled, the aforementioned can be partially or fully deactivated when so desired. Better than such deactivation is "activation," in the form of BMW's "Sport" driving mode.

Engaging the Sport mode requires no more than a button push, and voila; handling is crisper and engine response is sharper. The transformation is subtle but it's certainly noticeable, especially in terms of engine responsiveness. Power seems to come-on quicker, with less need to lay into the throttle. Steering response also feels more instantaneous, if that's possible given the Z4's already quick-witted reaction to steering inputs.

My preference in driving this week's tester was to leave good enough alone. With it's nannies engaged and the Sport mode at rest, the Z4 3.0si everything and more that most enthusiasts will ever want in terms of tenacious yet predictable, forgiving handling dynamics. And it's the latter that impressed me the most. The Z4 3.0si isn't one of those twitchy beasts that amplify every misstep into a potential loss of control. Rather it absorbs minor miscalculations without getting upset or displaying poor sportsmanship- and that inspires confidence.

The final handling frontier is that of braking. The Z4 3.0si is remarkably skilled and efficient at eliminating speed. No fanfare and no theatrics- just brutal easily modulated braking power. Again, confidence inspiring.

Comfort covered and uncovered

The outstanding handling ability of the Z4 comes at a price. Two things of note here: 1. Ride quality can be abrupt and choppy. 2. Tire ruts can play havoc with steering. Overall, the Z4's ride is not untoward or any less forgiving than other roadsters placing an emphasis on handling. It's the tire rut issue that's more of a bugaboo for me.

Care must be taken when driving on rutted pavement. The Z4 3.0si's 18-in X 8-in front and rear performance rubber like to misbehave when tracking heavily grooved pavement, making it wise to firmly affix two hands to the steering wheel.

My tester was equipped with a Premium option package that included a wind deflector screen that could be placed between the two headrests. When in place, the Z4 can be driven at highway speeds and above with very little turbulence or buffeting to interfere with conversation or hair positioning while the power operated soft-top roof is retracted.

The final word of Z4 3.0si praise goes to the optional M-Sport Seats that held me upright throughout the week. BMW makes great seats- what else can I say. The Z4 3.0si is a tremendously satisfying roadster, albeit costly. $60,900 for starters and $66,600 as tested.