Former world champion Nigel Mansell says IndyCar can learn from Formula 1 after the death of Dan Wheldon.
Briton Wheldon, 33, was involved in a 15-car crash in a race in Las Vegas.
Some IndyCar contests take place on oval circuits surrounded by a perimeter wall, while F1 races usually employ barriers well away from the track.
Mansell told BBC Radio 5 live: "In Indy racing, there is simply nowhere to go. When an accident happens you are into the wall in a split second."
Mansell, who won the F1 world title in 1992 and the IndyCar equivalent a year later, added: "This is why Formula 1 does an exemplary job. The tarmac runs off so the driver has time to decelerate the car."
The 58-year-old also said he agreed with the sentiments of former Formula 1 world champion Jody Scheckter, who after the death of Brit Wheldon.
Scheckter believes IndyCar is "the most dangerous motorsport in the world" because of the speed and number of cars on the track.
Mansell said: "To have 34 cars travelling at at 220mph on a mile-and-a-half long circuit, there are too many cars on the track.
"The trouble is there are no small accidents when accidents happen. There were a number of rookie drivers and others driving in their first race of the season.
"I heard Jody and he said it well. The smallest mistakes turn into catastrophic ones and Dan was on the receiving end."
Wheldon's death may have come in IndyCar but Sir Jackie Stewart still believes that the incident should serve as a warning to F1.
"We had very few people colliding with each other in my period of racing and thereafter," the former F1 world champion told BBC Radio Scotland.
"Now it has become somehow or other acceptable - and that is a warning. [Sunday's] accident is sadly a terrible wake-up call and they have to recognise the risk is very real."
Stewart added that he felt motorsport's governing body need to crack down on drivers who stepped out of line on the track.
"If drivers do consistently collide with each other, there should be heavier penalties," said the Scot.
"It should be marked down as something that just can't happen."
Derek Warwick, president of the British Racing Drivers' Club and a former F1 driver, claimed a host of changes are needed in IndyCar.
He echoed Mansell's concerns about the number of cars on the track in Las Vegas and feels F1 is safer because the drivers are better.
He told 5 Live Sport: "They do an enormous amount but they need to understand the quality of the drivers that are in the field as well.
"The drivers that go into a Formula 1 race are all great drivers who have won championships, from working their way up from Formula 3 to GP2 before they get a super licence to be able to race.
"I sometimes question the depth of talent in IndyCar races. The inexperienced generally end up having accidents. They need to tweak what they're doing a little bit."