AUDI ENTERS SUPERCAR FRAY WITH R8; Prototype previews Ingolstadt's bullish Porsche 911 challenger.

Byline: GREG KABLE

Look out Porsche-and for that matter, look out Lamborghini, Ferrari and Mercedes, too-there's a new German super-sports car maker in the mix and its name is Audi.

Ingolstadt's spectacular two-seat mid-engined R8 sports car, spied cloaked in spotted camouflage at first (above right), was later caught completely exposed as shown in these spy photos. Conspiracy theorists notice the timing of this wide-open view is highly suspect in that it seems to coincide with monthly buff-book deadlines for issues that will land at newsstands in June-just in time for Le Mans. But thanks to our shorter deadlines, we're blowing the R8's cover long before the annual French event.

Previewed as the Le Mans concept car at the 2003 Frankfurt motor show (where it claimed our Editors' Choice Best Concept award), Audi's Porsche 911 rival is expected to make its official debut at the Paris motor show in September. Mark mid-2007 for North American deliveries, according to one high-ranking insider who says the R8 will be the most expensive Audi model ever at more than $100,000 in base trim.

The production car adheres closely to the look of the Le Mans show car-at first glance it is hard to pick out differences between the two. Closer study reveals details are altered. The production model has an aluminum body among other features, though the silhouette and proportions remain.

Based on the same aluminum space frame and four-wheel-drive underpinnings as the Lamborghini Gallardo, the R8 spearheads a major new model thrust by Audi (see sidebar).

"By 2015 we plan to expand from 22 models to nearly 40,'' says chairman Martin Winterkorn. "Volumes will almost double from today's level.'' Those are big ambitions for a company whose U.S. reputation, rightly or not, is as a second- tier choice among its German competitors.