2005 BMW Z4

Cornering the Roadster Market

Few companies get to corner an entire segment of the market. Leave it to BMW to do it twice in a decade.

Performance

Ah, the goods.

No question, the Z4 is a performance automobile, one designed to really be a blast to drive, and one that smacks around the competition a bit as well. It's not the fastest roadster in this segment -- that title belongs to the far pricier, $52,365 Boxster S. But the more expensive Z4 3.0i ($40,945) is plenty quick, and even the $33,395 Z4 2.5i, although not as muscular, has plenty of grip, excellent steering and can swallow a windy road near flat-out without wallowing even slightly on its suspension.

Both cars, in fact, can do this and still feature setups that just don't bat around the driver. Compare this to cars like the Boxster and Boxster S, and, yes, you give up a small degree of performance edge, but you'd probably only discover this on the track. And both of those Porsches are bit harder on their passengers; driving them all day on anything but glass-smooth highways will tire you out. You might enjoy these cars -- no doubt, we do -- but for a daily driver we'd side with the BMW. Now if we lived in Southern California, with its never-frozen roads, the story would be different. Explaining precisely how the Z4 manages to be both agile and forgiving, as well as tight in a sharp curve, would take a while, but here are the keys:

• BMW used structural reinforcements (Y-form front longitudinal members; various braces) pioneered on the $130,000 Z8 and also those used in M3 models. Front strut towers are braced from the front suspension to the cowl.



• Forged aluminum lower arms (front suspension) that reduce unsprung weight (the amount of mass you have to move around when you steer).



• Hollow strut rods that also reduce weight



• Multi-link rear suspension with a wider footprint and three links per wheel. For better cornering stability, both rear wheels are canted slightly inward.



• The suspension was engineered from the beginning to work with run-flat tires, so the ride is no harsher than that of a sports car mated to conventional tires.

Add all that up and attach it to a frame that's 100% stiffer than the Z3's, and you have a convertible that feels incredibly solid and nailed to the road. That's very rare, and the confidence it inspires in a tight turn is unbeatable.

Of course, it wouldn't matter one whit without the two engines you can get with the Z4 and the transmissions these cars come with.

 First, the transmissions. Whether you get the five-speed available in the Z4 2.5i or the six-speed in the Z4 3.0i, both feature a clean, exact feel and are linked to lightly sprung clutches. These cars shift like BMWs, which is to say, like the gold standard for manual-shift cars. Incidentally, you can also get an excellent five-speed Steptronic automatic, and although we'd prefer to shift ourselves, this gearbox is about as much fun as any self-shifter because it allows the manual selection of gears and holds them. It doesn't anticipate the next gear and upshift when you don't expect it.

Also, next spring you'll be able to get either car with a Sequential Manual Gearbox (SMG) that works like a Formula 1-style clutchless manual. Gear selection is via two paddles adjacent to the wheel, and no clutch pedal is required. Prices for this option will be announced later.

Engines?

Yes, the Z4 2.5i has the same motor you'll find in the BMW 325i sedan, and the Z4 3.0i has the same engine as the 330i sedan. But both Z4s are as much as 500 pounds lighter than those sedans. And the 2.5-liter inline six in the Z4 2.5i gets changed intake and exhaust systems for greater low-end response. Indeed, although the torque peak (175 foot-pounds) arrives at a fairly high 3,500 rpm, most of that twisting force comes in right from a rolling start.

So even though 0-60 mph takes 7.1 seconds in the manual version of this car, which isn't world class, the mid-line power (for passing, say) is excellent and will nail you to your seat back. The Z4 2.5i will be the one most buyers pick due to its lower price tag, but it's hardly a wimp. Its engine is free-revving and entertaining. It can get a bit noisy at 80 mph on the highway, but the inline six is so smooth that even at such speeds the car isn't deafening.

The 3.0i is much quicker: 0-60 mph takes only 5.9 seconds in the six-speed car, and mid-range torque (214 foot-pounds) is a delight; power for passing in any gear is plentiful; and accelerating in this car is pure, stomping fun.

Both cars are available with a Sport Package ($1,500 in the 2.5i; $1,200 in the 3.0i), and we'd say this is a must. It buys bigger wheels and tires and a firmer sports suspension, but the real perk is the Sport button next to the gear selector. Press it, and the throttle is set for quicker response. This "wakes up" the engine, so a simple tap of the gas gets you going. The electric power steering also gets a little less assistance, so you feel the road a tad more. Doesn't sound like much, but in action Sport mode is like a hit of caffeine for a car that's already wide-awake.