The category has gone through several rule iterations since then with domination by Capris and Triumph Dolomites in the 1970s under the Group 1 era into Group A in the 1980s, which thrust Rovers and BMW to the forefront.
Despite those slick-tyred cars ruling the roost in terms of race wins, the lower-powered classes were rewarded with as many points as the overall race winner, so the champion often came from the tiddlers at the back of the grid. Nevertheless, at the end of the Gp A era, which came in 1990 with the mighty Ford Sierra RS500s, a lap of Thruxton could be despatched at an average speed of 105mph.
The ultimate expression of a touring car has to be a single-class iteration dubbed the Super Touring era, which ran between 1991 and 2000. They were all two-litre cars but with sophisticated aerodynamics and a raft of professional drivers and teams. The series’ popularity peaked when nine factory teams (Alfa Romeo, BMW, Ford, Honda, Peugeot, Renault, Toyota, Vauxhall and Volvo) entered the category in 1995.
Lap times tumbled as the budgets shot up, but the writing was on the wall as the costs were becoming unsustainable. The BTCC was becoming all about pure-bred racing cars rather than road-based race-tuned motors.
The fastest-ever touring car lap at Thruxton was set by Jason Plato in a Vauxhall Vectra in 2000. He was helped by the fact that the Tarmac had recently been relaid, but he pounded around the 2.36 miles in 1min 13.272sec, or an average speed of 115.75mph.
When the bubble burst, bosses reined in the spending by introducing control parts. That has evolved into the regulations we have today with mandated front and rear subframes, electronics, gearboxes, clutches, tyres and brakes. In turn, it has pegged times and speeds back to a still very acceptable 109mpha average around Thruxton.
But, as two-time champion Plato says, the effect of the modern rules has been to the benefit of the championship. In a feature in this week’s Motorsport News, Autocar's sister publication, the works MG driver says: “It does feel slower today, but only because I know how frenetic it was to drive a Super Tourer on the limit. But the racing now is as good, if not better, than it was back then.
"It might be slower but I think the modern cars are more spectacular for fans because there is much less dependence on aerodynamics and it is all about mechanical grip. That means the cars slide and move about more. That’s what the fans love.”
And giving the fans what they want is one of the strongest calling cards of the BTCC, no matter how fast the cars are.