The "e-booster" is Volkswagen’s speak for an electric compressor that is placed between the induction system and intercooler, which uses electricity to spin the turbine vanes of a smaller turbocharger that will route air to the main compressor in moments where there isn’t enough exhaust pressure to build up its boost. Effectively with the aid of this electrically-driven compressor, the e-booster could pump in the air pressure needed to drive the exhaust gas driven turbo, thus eliminating the turbolag that is characteristic of all big turbochargers. In effect, this setup gives drivers an instantaneous engine response similar to that of a non-turbocharged engine, while allowing engineers to fit a bigger turbocharger to extract big power figures from relatively tiny engines.
Tech aside, little else is revealed of the three-cylinder engine, besides it being based on the current EA211 engine family, and features engineering and know-how lifted from the Polo WRC’s rally-spec engine. For now, Volkswagen says that the tiny three-cylinder engine is only a demonstration of the potential of petrol combustion engines, but the prospect of having a thrumming little three-cylinder engine with 272PS on tap, is one that would be too good to pass off for German giant.