Koenigsegg CCR

Koenigsegg's CCR engine: an 806 HP Aluminum 90 Degree, Supercharged V-8 (with Dry Sump Lubrication).
Regretfully CCR is not a street-legal supercar, however Koenigsegg is already working on the solution to this problem. At the recent Geneva Motor Show, they unveiled the Koenigsegg CCX, a derivative of its CC family which is street-legal supercar for the U.S. roads.
Made in Sweden.

Mercedes-Benz SLR McLaren

Engine: 5.5 liter Supercharged V-8.
Mercedes-Benz SLR McLaren has been on world's fastest and most expensive cars lists for quite a while now. This car is a fascinating result of a collaboration between two well known car brands: Mercedes and British race car legend McLaren. The delightful SLR McLaren is probably the most sophisticated and comfortable of all street-legal race cars to date. In 2007 most expensive car list this supercar is most likely going to be replaced by its successor Mercedes-Benz SLR 722 Edition.

Porsche Carrera GT - $440,000

Engine: V-10, DOHC 5.7 liter. Its ten-cylinder engine produces 600hp - the type of power that can rarely be seen outside the racing world.
Although some well known auto portals claim that Porsche has stopped selling its Carrera GT supercar. But currently (2006 Dec), Porsche confirms that its $440,000 famous convertible is still available for sale in the U.S. market, thus the car qualifies to be in this list.
Made in Germany.