The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered (downspeeding).
The layout brings the ability to shift in a non-sequential manner – going from gear 8 to gear 2 in extreme situations simply by changing one shift element (actuating break B and releasing clutch D).
[8] In order to increase the number of ratios, ZF and consequently GM have abandoned the conventional design method of limiting themselves to pure in-line epicyclic gearing and extended it to a combination with parallel epicyclic gearing.
On the other hand the selected gearset concept offers 2 to 3 gears more than conventional transmissions of comparable manufacturing costs, which more than compensates for the weaknesses.
R & Even The 8L 90 is the subject of a class-action lawsuit filed in December 2018 that alleges the transmission suffers from persistent "shudder" issues and that GM has known about the problems since its introduction and has failed to provide a solution, instead choosing to wait until the unit is out of warranty.