Developing 225kW and 407Nm of torque, the N55's numbers fall a little short of the current generation N54, but the single turbo brings peak torque online 100rpm earlier than the current twin-turbo six.
Owners of next-generation BMWs featuring the newer engine can look forward to less turbo lag and - thanks to the integration of BMW's VALVETRONIC system - better throttle response and greater fuel economy.
Improving fuel efficiency further, the 135i Coupe and Convertible will both get BMW's seven-speed Double Clutch Transmission (DCT), including the revised paddle system that sees down shifts on the left and up shifts on the right.
No hard figures for the N55's fuel consumption have been released, although reports last year claimed the N55-powered 535i GT will achieve around 11 l/100km.
BMW has yet to reveal the styling for the upcoming second generation 1 Series, but bodystyles will likely cover the same range offered by the current model.