Brands Hatch usually attracts a healthy turnout, and this event was no exception. Out of 30 entries, 25 cars materialized, and the organizers had announced that there would not be a limit to the number of cars allowed to race.
Brabham: Jack Brabham's car was fitted with inboard rear brakes, to save on unsprung weight and improve response on the bumps.
BRM: All three cars had revised gear linkages, after the problems suffered by Pedro Rodríguez in France. The team had been having problems with oil surge, so the sump and tanks had been redesigned, with different variations being tried.
De Tomaso: The team returned after the tragic loss of Piers Courage, using the second car that was run at Brands earlier in the season. Brian Redman, who it was revealed had turned down an offer to join Tyrrell after Monaco, was driving the De Tomaso here. This car featured a narrower track than the older car.
Ferrari: Clay Regazzoni was back in the second car. The team had been having problems with oil surge similar to BRM, so the oil tanks had a revised baffle configuration.
Lotus: Jochen Rindt's 72 was seen with a fiberglass air intake box, drawing air into the engine from both sides of the roll bar. This was the first example of what eventually became a required part of every F1 car. The 49C that had been driven by Alex Soler-Roig earlier in the season was entrusted to Formula 3 champion Emerson Fittipaldi here, and was looking much more carefully prepared.
Graham Hill's 49C had some revised suspension components from the factory.
Pete Lovely made his final European appearance of the season, but his 49B was definitely showing it's age.
March: The Race of Champions had shown that the Marches had serious suspension issues on bumpy tracks like Brands Hatch. All of the cars had some form of revised suspension (the factory had a kit available, but their own cars were not using it), and a great deal of experimentation went on during practice. Jo Siffert was driving a new monocoque after his accident in France.
Both Tyrrell cars had made their own modifications to the rear suspension of the cars, and the team was experimenting with inertia switches for the fire extinguisher on Jackie Stewart's car.
Ronnie Peterson's car was the only one to use the revised rear suspension offered by the factory without modification, so it became the baseline by default. Peterson was actually faster than the factory cars in practice.
Mario Andretti's STP team had completely rebuilt and modified the car on their own during testing in the US since it was last seen at Spain, and the changes were noted with interest. This car was faster than all of the Marches except for Stewart's.
McLaren: The two Cosworth powered cars were unchanged, but the Alfa Romeo car of Andrea de Adamich had been having similar oil surge problems as the 12-cylinder cars. Alfa Romeo had redesigned the oil tank and sump systems, but the larger tank required a higher ride height than the other cars.
Surtees: John Surtees became the fourth driver (after Jack Brabham, Dan Gurney and the late Bruce McLaren) to drive in Formula One in a car that his own team manufactured, with the debut of the new Surtees TS7. The car looked well prepared, but needed further development, so this weekend was a big test session for the team.