In the wake of this April’s major recall of 598,000 full-size trucks and SUVs due to issues with their 6.2-liter V-8 engines, General Motors is now facing a new class action lawsuit.

U.S. Class 8 retail sales closed in on nearly two years of year-over-year declines in April, according to data from Wards Intelligence. Sales decreased 8.7% to 18,078 units from 19,798 in April ...