Navistar will remain the exclusive provider of Class 8 tractors for truckload carrier Heartland Express
, Navistar announced. In a new agreement, Heartland Express will take delivery of International ProStar+ tractors with EPA 2010 MaxxForce 13 engines.

Based in North Liberty, Iowa, Heartland Express specializes in time critical shipments for shippers in the U.S. With this order, the Heartland Express fleet will soon be entirely comprised of International ProStar and ProStar+ tractors.

"Having fuel-efficient, cost-effective trucks that are embraced by our drivers is a top priority for us," said Russel Gerdin, chairman and CEO, Heartland Express. "This agreement with Navistar will ensure that we have the most complete fleet of fuel-efficient and driver-friendly trucks in the industry for years to come."

The ProStar+ offers new aerodynamic enhancements, including optional full-length chassis skirts for sleepers as well as a new cab roof air fairing for day cab models. The ProStar+ provides an extra 1,300 pounds of added payload capacity and fuel economy benefits, the company claims.