The idea itself is not new, however. It originated in the 3rd century BC and has been used since Euclid postulated his geometry around that period. Mathematically, it divides a line into an extreme and mean ratio, roughly three to five. This "art equation" was used in the design of the Parthenon where the Greek thought it embodied some "harmonic proportion which is in tune with the universe."

Poetically, says Cadillac, it's an expression of the intersection of art and science. And so it implies the blending of fine engineering and body styling from Cadillac's design studios (See Machine Design, Nov. 18, 1999, page 168.)

But what we have to look forward to in the near future is Cadillac's vision to work the "science equation" which includes more development in active safety, precise all-weather control, and infotainment.

The vehicle I tested has an advanced navigation system, and I had a great time with it. A 5-in. color screen sits in the middle of the instrument panel, accessible by both passenger and driver. It displays touchscreen operating controls as well as the navigation map and shares the Bose music system.

Digitally encoded map information for various regions of the country are stored on several CD-ROMs. I was impressed by how easy the system is to use, as well as its accuracy. After programming the present location and the destination, you are given several options for the type of route to take such as all freeways or more scenic roads. A cursor shows your position on a road map that moves occasionally to keep the cursor on screen. Manual interaction is limited once the car is moving, but one control that's active, however, is the zoom button. It lets you set the amount of distance resolution you want on the screen, such as 1 in. equals one mile, 10 miles, or 100 miles.

When approaching a programmed entrance or exit on the freeway or a road intersection, a pleasant voice alerts you that a turn is just a few yards ahead. Another warning sounds when you're closer, and finally a last warning when adjacent to the turn.

Moreover, when driving past the programmed turn, the computer recalculates the route based on your new position, and eventually directs you back to the preplanned route. And it is relentless. No matter how many times you try to confuse the computer, it tells you how to return to the original computed route.

The navigation system costs about $2,500, but if you can afford a reasonably outfitted Seville in the first place (just under $55,000), I would highly recommend this outstanding feature.