In its base form, the Leon Cupra 280, which was introduced in 2014, made 276 horsepower (206 kilowatts) and 350 Newton-meters (258 pound-feet) of torque from its turbocharged 2.0-liter TSI engine. However, this unit used in the top-speed run was tuned to a bonkers 520 hp (383 kW) and 600 Nm (443 lb-ft) of twists.
That tuning was done by KolbenKraft, a German after-market/tuning firm. With the upgrades, the hatchback's top speed has been updated from 250 km/h (155 mph) to 300 km/h (186 mph). For comparison, the Mk8 VW Golf R 20 Years Edition, which is the most powerful production Golf in history, is electronically limited to 270 km/h (168 mph) only.
After a few attempts, AutoTopNL eventually made it and maxed out their Leon Cupra's speedometer. Given that the speedometer was not able to show its readings accurately, we reckon it might've gone over 300 km/h! We wouldn't be surprised either; this vehicle is something special after all.
Source: Motor1