At the age of eight, he began his racing career, racing go-karts. He earned a factory ride after his first year of racing. In 1994, his karting career ended with 10 National Championships and 14 State Championships to his name. At the end of 1995, he started racing late models at Old Dominion Speedway in Manassas, Virginia. He was rookie of the year in 1996, and finished third in points. In the 1997 season, he captured 9 wins, and 27 top 10 finishes, at several tracks throughout the south. He finished second at points at Old Dominion.
In 1998, he ran select NASCAR Busch Series events, along with 15 late model races throughout the east coast. He qualified for several Busch Series events. In 1999, he did not run any NASCAR events, but finished fourth in points at Old Dominion, and set a new track and LMSC record of 15.222, which still stands today. He continued to run late model and off and on Busch Series events through the 2003 season, when he won the national championship for LMSC in NASCAR. In 2004, he raced first for Jim Harris in the Craftsman Truck Series in the Harris Trucking Dodge. Then about mid season, he was picked to be one of the 4 Hungry Driver drivers in Tommy Baldwin Racing's No. 6 Busch Series Dodge's. He then moved into the USAR Hooters Pro Cup Series in 2005 driving the Winfuel No. 32 Chevy for Dale Earnhardt, Jr. Ken Barlow hand-picked Jefferson Hodges as the teams crew chief, saying, "Jefferson did a fabulous job building and leading this new team with knowledge and a true craftsmanship". In 2006, McFarland was hired to drive the No. 88 United States NavyChevrolet for JR Motorsports in the NASCAR Busch Series. He was injured while running in the top 10 at the Milwaukee Mile and missed the next two races at Daytona International Speedway and Chicagoland Speedway. He had dislocated his shoulder and also injured some of the muscles around it. Following the Kroger 200, he was released from his driving duties of the No. 88 U.S. Navy Chevrolet. Martin Truex, Jr. would drive the car in the next race at Watkins Glen International and Robby Gordon drove it in subsequent races at Michigan International Speedway and California Speedway. Shane Huffman, also from the Hooters Pro Cup Series, drove the remaining races in the No. 88.
Post-racing career
McFarland served as a crew chief for Ben Rhodes when Rhodes won the 2014 NASCAR K&N Pro Series East season. For 2015, McFarland served as crew chief for Justin Haley's East Series team. He served as the general manager for his partly-owned team, MDM Motorsports, for two years. McFarland later returned to crew chiefing by joining Joe Gibbs Racing as the team's crew chief for its ARCA Racing Series efforts.
Honors
As part of the 25th anniversary of the NASCAR Weekly Series in 2006, McFarland was named one of the series' All Time Top 25 drivers.
