For a mid-summer run on the Berkshire back roads to a Saturday evening performance by the Boston Symphony at Tanglewood, it would be difficult to beat my TTS roadster. The top was down, the stereo was pumping out classical tunes from Sirius satellite radio, and the brilliant red TTS was the best looking car on the road — though not so good looking as to attract the attention of any Massachusetts state police, who were anyway otherwise engaged directing concert-going traffic.

The “S” designation identifies the sport version of the well-known TT roadster. An $8,200 bump in the base price gets you a pumped-up version of Audi’s 2.0 liter turbocharged engine that puts out 265 horsepower (vs. 200 hp in the TT) as well as a host of appearance features like 19-inch 7 twin-spoke wheels. Audi doesn’t make any ugly cars, and the front end, with a body-colored bar bisecting the iconic horseshoe grille, is the brand’s best looking.

The Quattro all-wheel drive system keeps the TTS planted through the tightest curves, and acceleration at higher revs is impressive. There is one important performance exception, though: The turbo is slow to spool up at low engine turns, creating sponginess underfoot and uncertainty before you attain cruising speed. I eventually discovered that a slow, even throttle advancement produced better results than an impulsive stab. But I missed the feeling of power under pedal I remember from a Porsche Boxster.

With its stubby but refined bubble shape, the TT is a modern design classic whose looks are only improved in this latest version. And thank goodness Audi didn’t follow BMW by adding a power retractable hardtop. The TTS’s convertible fabric roof is as tight as it needs to be and raises and lowers in seconds, never impinging, needless to say, on the surprisingly commodious trunk.

Owning a TT is a very special experience these days. Only 951 new ones changed hands during the first half of the year, only a fraction of those were roadsters, and only a fraction of THOSE were ”S” roadsters. The $55,075 sticker price for my test car gives you one big clue why. Still, there is nothing else quite like it on the road, and I can begin to justify the purchase to myself if I think about it as an investment, like a mechanical Swiss watch, to be handed down to future generations.

If that proves inadequate, I can always plan more trips to Tanglewood.

It is rare that the appearance of a car isn’t diminished by the addition of a retractable hardtop roof. The storage requirements for all that metal and machinery usually dictate a wider and higher rear end than is esthetically desirable. Check out the Chrysler Sebring convertible for an especially egregious example.

Not so with the newly grown-up Z4, which may be the best-looking BMW of all. Its tightly-tailored butt is balanced by a long, long front end, with attractive accent lines on the flanks. The effect is to create a modern car with classic proportions. Think pre-war Mille Miglia.

The Z4 interior closes the deal. It combines intelligent functionality and helpful info-graphics with a stylish touch not seen in earlier models, which to my eye were obsessively Spartan.

The Z4’s good looks are combined with stylish road matters. My test car was powered by a 3.0 liter, 255-horsepower inline-six. (The 300 horsepower twin-turbo six is also available). With the automatic transmission, the 3.0 is reported to get the car to 60 miles per hour in six seconds flat. The steering is typically precise, and the suspension produces a nice blend between a sporty ride and one that is comfortable. Mileage is a none-to-shabby 19 miles per gallon city/29 mpg highway.

All of this excellence comes at a price, both financially and functionally. While the base price of the Z4 is $45,750, my test model with the smaller engine came in at nearly $60,000, which included $500 for heated front seats and $350 for a high-definition radio.

That helps explain why Z4 sales are less than robust: BMW sold 361 in July. By comparison, it sold 427 X6s and 807 7 series.

Then there is the matter of trunk space. You’d never get a bag of golf clubs into the trunk of a Z4, but with the top down, you’d have a hard time even squeezing in a shaving kit. That puts a limit on the places you’ll go.

Sadly, the combination of price and space limits the appeal of the Z4 to a very small number of owners. Too bad. A car this good deserves a wider audience. Perhaps this leaves an opening for BMW to bring back the old cloth topped, four-cylinder Z3, with a smaller price tag and more room in the rear.