Take a very good look at the 2019 Subaru STI S209 at the 2019 Detroit Auto Show because your chances of actually seeing one on the road are somewhere between slim and none. Subie only intends to bring "around 200" of these highly modified saloons into the U.S., so chalk this one down as another piece of forbidden fruit for the UK.

Because of the extensive amount of work on a standard WRX STI to turn it into the S209, Subaru actually badges this "handful" of vehicles as an STI-branded vehicle in the U.S. 

The S209 packs a heavily modified version of Subaru's familiar EJ25 2.5-litre boxer four-cylinder. The overhaul includes a larger turbocharger, revised intake, forged crankshaft and pistons, hand-polished tubular headers, and a lightweight exhaust. The result is a mill making 341 bhp, rather than the stock 310 bhp. A six-speed manual sends the output to the company's familiar all-wheel-drive system.

Gallery: 2019 Subaru Impreza WRX STI S209

The S209 should be a sharp handler after STI's hard work. The suspension comprises Bilstein dampers and stiffer springs. Extra chassis stiffening comes from a front strut tower brace and front and rear draw stiffeners. The special model's wider body kit lets the engineers expand the front and rear tracks by 15.2 mm. A set of forged, 19-inch BBS wheels wears bespoke Dunlop GT600A tyres. In all, this setup lets the S209 achieve over 1.0 g of lateral grip.

STI doesn't neglect the S209's braking, either. There are cross-drilled rotors with six-piston front calipers and two-piston units at the rear. High-friction brake pads make the most of these stoppers.

Subaru isn't announcing pricing yet. However, there are enough hardcore fans of the brand who would want such a low-run vehicle that we can't imagine the company having any problem selling the entire production run very quickly.