Bentley debuted in CART in 1990 with Spirit of Vancouver, a program specifically created to field a Vancouverite in the inaugural Molson Indy Vancouver. He returned to the race the following year, with the effort receiving support from Dale Coyne Racing.
From 1992 onwards Bentley expanded his CART schedule with Coyne, running seven races that year including Vancouver, where he finished fourteenth despite managing a back injury. He continued with the team in 1993, but a serious incident during Indianapolis 500 practice hospitalized him: a fuel regulator split and poured methanol into the cockpit, causing burns to his hands and neck. He pressed on with Coyne in 1994, the year the team gained Pro Football Hall of Fame running back Walter Payton as a co-owner under the Payton Coyne Racing banner, though outdated equipment limited competitiveness.
Sponsorship difficulties forced Bentley out of IndyCar for 1995. He competed in sports car racing and the World Sportscar Championship before returning to CART at Vancouver with Payton Coyne, failing to make the field after setting the slowest qualifying time. He subsequently focused on endurance racing, winning the 1998 United States Road Racing Championship in the GT3 class and the 24 Hours of Daytona in 2003 in the SRPII Class.
Bentley worked as a driving instructor at his Performance Advanced Driving School and as a technical columnist for racing clubs throughout the 1980s. In 1998, he published the first volume in what became the Speed Secrets series, a collection of books on racing technique and strategy that eventually ran to nine volumes. Titles include Speed Secrets: Professional Race Driving Techniques, Inner Speed Secrets with Ronn Langford, The Complete Driver with Bruce Cleland, and Ultimate Speed Secrets: The Racer's Bible, among others. He also co-authored a book with Bob Bondurant on race kart driving, and in 2017 published Performance Pilot with professional aviator Phil Wilkes, extending his methodology to aviation.
Through his consulting business, Bentley Performance Systems, Bentley applies the mental and technical disciplines of racing to executive, business, and sports coaching. His methodology draws a direct line from racing driver focus and precision to high-performance decision-making in other professional domains.
Bentley occupies an unusual position in motorsport: a credible CART competitor who turned his racing knowledge into an enduring body of instructional work. The Speed Secrets series in particular has remained a reference for amateur and club racers for over two decades, making his influence on driving technique arguably broader than his on-track results. He lives in Issaquah, Washington.