The i3s features a little more power from its electric motor with output increasing to 181 horsepower and 199 pound-feet of torque.
Base versions of the i3 are rated at 170 horsepower and 184 pound-feet of torque.
BMW says the i3s can hit 60 mph in 6.8 seconds, while the base car needs 7.2 seconds.
As with the base car, the i3s can be optioned out with a two-cylinder gas engine to serve as a range extender.
No official range figures are available yet for the full EV model, but BMW says the i3 should be able to travel about 97 miles on a full charge.
Suspension enhancements include different springs, dampers, antiroll bars and 20-inch wheels.
A Sport mode quickens throttle response and tightens steering characteristics.
Specific visual changes in addition to the 20-inch wheels include a different front spoiler, black-painted kidney grille, extended wheel arches and rear spoiler.
No official on-sale date has been announced, but BMW says it is shooting to have the new i3s in dealers in January or February.
The 2018 BMW i3s starts at $47,650. Destination costs are an additional $995.