Lunn joined American Motors in 1971 as the director of engineering for
Jeep, which had recently been purchased by AMC from Kaiser. Lunn quickly advanced at AMC to the position of Vice President of Engineering. His notable accomplishments include the
AMC Eagle, the compact
Jeep Cherokee (XJ), which was the first of the modern range of SUV vehicles, as well as the development of the
AMC Straight-4 engine and the Jeep 4.0-liter engine that were based on the "modern era"
AMC Straight-6 engine. As Jeep's chief engineer, Lunn orchestrated 4WD's next leap ahead when he joined the
AMC Concord body with a reconstituted Jeep driveline. According to former AMC chairman,
Gerald C. Meyers, "our initial reaction to Lunn's concoction was, 'What the hell is it?' The body was raised an extra four inches for transfer-case clearance and the wheel wells were wide open." This became the AMC Eagle, an integration and application of AMC and Jeep engineering technologies, which was America's first four-wheel drive car. Lunn was also active in the
Society of Automotive Engineers (SAE International) becoming their technical committee chairman in 1983. He was elected a Fellow of the Society in 1985. He completed his career at American Motors by forming and becoming President of Renault Jeep Sport to centralize all AMC and Renault racing activities in the U.S. Lunn also designed and put into production a low-cost racing car for the
Sports Car Club of America (SCCA), of which more than 864
Sports Renault purpose-built race cars (later:
Spec Racer Ford) have been built. Lunn developed a groundbreaking design for a compact-sized SUV. It featured a steel ladder frame welded to a unitized body and included a four-door version. Because AMC lacked the resources to conduct the lengthy durability tests before the late 1983 introduction of the Cherokee XJ, Lunn headed the first American entry to drive the
Paris-Dakar rally. The objective of his team was "not to compete but simply to run the brutal desert course" with two new Cherokees and monitor how they would survive the punishing racecourse. Lunn's design "became the template for the modern SUV and continues to be copied by virtually all major global automakers." He retired in 1985 and was immediately called back to become vice president of engineering for the
AM General division of AMC. The
High Mobility Multipurpose Wheeled Vehicle military Jeep (Hummer) was going into production and Lunn was charged with overseeing the corrective actions to achieve acceptance by the U.S. Army. == Retirement ==