Powered by a 3.0-litre V6 turbo-diesel, the GLC350d develops 190kW of power and 620Nm of torque, mated to a nine-speed automatic transmission as standard.
Sending drive to all four wheels, the GLC350d SUV and Coupe can sprint from 0-100km/h in 6.2 seconds, while using a claimed 6.3L/100km on the combined cycle.
Starting at $89,900 plus on-road costs for the SUV and $99,900 plus ORCs for the Coupe, both models are around $16,500 dearer than their equivalent GLC250d variants.
However, the extra spend does bring air suspension, Comand Online infotainment and a 13-speaker Burmester surround sound system in both models.
The conventional SUV body style also gets a sporty AMG Line exterior body kit with 20-inch AMG alloy wheels, a flat-bottomed sports steering wheel with paddle shifters, and AMG floor mats - all of which is already standard on the Coupe.
The new arrivals slot in between the GLC250d and AMG GLC43 variants in their respective ranges.
2018 Mercedes-Benz GLC pricing
GLC220d - $67,500
GLC250 - $70,612
GLC250d - $73,200
GLC350d - $89,900
AMG GLC43 - $102,112
AMG GLC63 S - $164,900
GLC220d - $78,500
GLC250 - $81,211
GLC250d - $83,500
GLC350d - $99,900
AMG GLC43 - $109,611
AMG GLC63 S - $171,900
All prices exclude on-road costs