Base-model cars rarely get a second glance from enthusiasts, but every now and then an entry-level vehicle shows up whose easier-to-swallow sticker price serves merely to accentuate its excellence, not define it. Like the Mercedes-Benz E320, the subject of last week's Just Driven report, the BMW Z4 2.5i is just such a car. The performance gulf between our test car and the top-trim Z4 3.0i is narrower than their $7150 price difference would suggest. Both offer splendid in-line six-cylinder engines, exceptional material quality, and the peerless joy of open-air motoring. The 2.5i gives up 41 horsepower, 39 pound-feet of torque, and a sixth gear to the 3.0i, but still emerges as a well-appointed, wholly satisfying car. The 2.5i is pure magic on the road, better in every way than the old Z3 and very nearly as dynamic as the $9570-pricier Porsche Boxster. Yet despite all the things the Z4 2.5i does brilliantly, perhaps its greatest trick is something that it doesn't do: BMW's least-expensive roadster never makes its driver feel like he's settled for less. And that, in the end, is what makes it worth a second glance.