General Motors (NYSE:GM) said Chevrolet’s total sales are expected to increase 15% during the first half of 2011, driven primarily by cars, which are approaching their highest level of Chevy sales in 20 years.Chevy car sales are projected to be up 23% for the first six months of the year when June sales are reported on Friday.Truck utilities, and crossovers are expected to be up 9% over the first half of 2010.Chevy cars have outsold sales of trucks, crossovers, and utilities in the months of April, May, and June this year, and are expected to represent 47% of total sales for the 6 month period. That's the most since 1991, when cars were 52% of all sales.Alan Batey, U.S. vice president, Chevrolet Sales and Service said, "Chevrolet has always been known for building great trucks. Today, we are in the middle of transforming the brand with a strong lineup of cars that match the appeal of our trucks and crossovers.Shares of General Motors are trading up 0.2% at $30.36.