The Marr Auto Car was one of the world's first automobiles with an overhead camshaft (OHC) engine.

Possibly his most important achievement was building one of the first overhead valve engines (OHV).

This he did in 1898 when he built a trike that weighed 118 pounds, and whose single cylinder had a bore and stroke of 3 inches each.

[3] Marr also built a prototype Cyclecar in 1915 which was very narrow seating the passenger behind the driver.

[4] He had a cottage in Signal Mountain, Tennessee where he also built a large home in which to retire.