General Motors Co. posted a 4.6% increase in sales for the second quarter of 2018 amid a strong demand for crossovers and trucks.

The Detroit-based car company sold 758,376 vehicles during the quarter as compared to 724,925 vehicles in the year-ago period.

"Customers are buying with confidence because the economy is strong and they expect it to remain strong," said Kurt McNeil, vice president of U.S. sales operations at General Motors.

Sales of General Motors' flagship Chevrolet brand grew 6.2% during the quarter to 528,100 units, more than 497,159 units the company sold a year earlier.

The carmaker's sales were up 4.2% to 1,474,170 units for the first half of the year, spanning from January through June.

General Motors' Chief Economist Elaine Buckberg predicted a strong second half.

"Tax reform raised take-home pay, consumer confidence is high and household balance sheets are healthy," Buckberg said.

"All of this plus a strong job market makes consumers more willing to commit to major purchases like vehicles," she noted.

In April, General Motors said it will stop posting monthly sales figures.