Sir Jackie Stewart has questioned the safety of IndyCar racing following the death of Briton Dan Wheldon at the Las Vegas Indy 300.
Wheldon lost his life on Sunday after a 15-vehicle crash which caused his Dallara Honda to hurtle through the air and hit a trackside fence on lap 11 of the race, which was then cancelled.
The 33-year-old was airlifted to hospital but died from what IndyCar chief executive Randy Bernard confirmed were “unsurvivable injuries”.
Stewart, who won three Formula One championships for Tyrrell between 1969 and 1973, believes there are too many cars competing at too high speeds in IndyCar and certain problems need to be addressed.
“The accident we saw yesterday was something different,” he said.
“It was such high speed on such a small track with too many cars together and not that many top racing drivers in there.
“Take 15 cars out of a field of 34. It's probably too much for a one-and-a-half-mile circuit.”
But Stewart, who became an advocate for racing safety following his retirement in 1973, believes reducing the number of cars on the track is not the only potential solution.
“Problems really are made to be overcome. We can find better ways of doing things,” he added.
“It may be that we have to have smaller engines with smaller horsepower and slower speeds in IndyCar racing.
“Do we have to do 230, 240 miles per hour? We don't have to do those speeds. If all the cars were travelling at the same speeds, you could knock off 30 or 40mph from that speed frankly no one would notice.
“You've got to contain the action within the race.
“I don't think you can stand still for safety. There's always an improvement to be made.”
Stewart's call for change came after fellow former Formula One champion Jody Scheckter revealed he wants his son to quit “the most dangerous form of motor racing” in the wake of the tragedy.
Scheckter was a spectator at Sunday's race and faced an anxious wait before he found out his son Tomas had escaped unharmed from the fatal accident.
“I've wanted him to give up for a while,” Scheckter said.
“Hopefully this will knock some sense into him and realise there is more to life. It really isn't worth it.
“It is the most dangerous form of motor racing at the moment. I think the set-up they put in so it can be more of a spectacle makes it very, very dangerous on circuits like this. Some others [circuits] aren't as bad.”
Scheckter (61), who won the Formula 1 title in 1979, echoed Stewart's worries about the number of cars competing in IndyCar races at such high speeds.
“They were basically touching wheels at 220mph. They all bunch up together so there are 34 cars in a small space of track.
“One person makes a mistake and this happens. You [shouldn't] have to get killed if you make a mistake. It was madness. Formula 1 is not like that any more and it is still quite exciting.”
Former World champion Jenson Button paid tribute to Wheldon on Twitter. The pair were rivals on the track in the early stages of their careers.
Button wrote: “Just woken up to the most horrific news.. Dan Wheldon RIP...
“I have so many good memories of racing with Dan in the early 90s, a true fighter. We've lost a legend in our sport but also a great guy.
“I can't begin to imagine what his family are going through and my thoughts are with them at this very difficult time.”
Clive Wheldon, father of the IndyCar driver, paid tribute to his son, describing him as a “true champion” and a “gentleman on and off the track”.
Speaking outside the family home in Emberton, Buckinghamshire, he said: “The family would like to thank everyone for their overwhelming outpouring of sympathy.
“Daniel was born to be a racer and yesterday left us doing what he loved to do.
“He was a true champion and a gentleman on and off the track.”
New York Times reporter Curt Cavin described the shock at the track in Las Vegas as the cars performed a five-lap salute after the race had been abandoned.
“The drivers gathered and decided the salute was the best they could do at the moment. Fans remaining in the grandstand stood, reverently at first, then applauding as Amazing Grace played on the speedway's PA system.
“Those involved with the sport stood at the edge of pit road, holding hands as the cars rolled by. There were hugs, tears, stares.
“How could this be? There were no answers.”
In Wheldon's adopted home of St Petersburg, Florida, Mayor Bill Foster told the Tampa Tribune there would be a tribute organised for their adopted son.
“He was our hometown hero when it came to racing,” Foster said. “He was just like us. He didn't want the limelight ... when he took the helmet off.”