Ford Motor Company [NYSE:F] is out testing a more extreme version of its Focus RS thought to be a successor to the previous generation Focus RS500. The tester was sporting some new vents on the hood as well as a larger rear wing.

According to Autocar, the tester is in fact for an RS500, which could potentially arrive on the market as early as next spring. The British publication reports that production will depend on whether the project makes financial sense and if it can go ahead without too much disruption to the Focus production line in Saarlouis, Germany.

The engineers are said to be aiming for as much as 400 horsepower from the regular RS’s turbocharged 2.3-liter inline-4. That’s up from the engine’s current 350-hp rating and would likely see performance numbers improved from the current 4.7 seconds for 0-62 mph acceleration and 165 mph for top speed.

Sadly, production is likely to be limited to just 500 units. Of course, you don’t need to upgrade to a RS500 to get more performance out of the regular RS without busting the warranty. Ford-tuner Mountune is already offering factory-backed upgrades that boost output to 370 hp.

The RS500 would be a great way to send out the current Focus which is due to be replaced by a successor in 2018. Test mules for the successor have already been spotted.