Given the hot tempers, dramatic finishes and contentious rulings IndyCar has already delivered this season, there's at least one thing the drivers can agree on: The drama isn't going to cool down up north in Toronto on Sunday

"There could be carnage," veteran driver Sebastien Bourdais said.

He was referring to IndyCar's decision to reinstate its push-to-pass feature, providing drivers an additional boost of horsepower to assist in making passes. That extra speed will be available to everyone navigating the twisting, narrow, slick, 11-turn, 85-lap, 1.75-mile street course with a reputation of getting both the best and worst out of drivers.

Last year's race, won by Dario Franchitti, featured eight cautions and had six cars fail to finish because of accidents. And Franchitti's victory wasn't a clean one.

Will Power accused the Scot of being "dirty" for how Franchitti spun him around in making a pass on the 57th lap. And Power's day ended a few laps later, when he was spun out into the barriers by Alex Tagliani.

Don't think for an instant Power has forgotten.

"You look at it, take what you can from it," he said. "It's helpful, that's all you can do, because if you try to think about it and get (angry) it's not going to help you."

Good luck with that.

They couldn't get through two practice sessions Friday without a bump between Power and rookie Simon Pagenaud, who had the second-fastest car of the day behind Indianapolis 500 champion Franchitti, also the 1999 and 2009 Toronto winner.

"I don't know, you'll have to ask him," Pagenaud said. "I don't know what he was thinking but it was a pretty aggressive block, and it was definitely pretty slow there. I don't know."

Power, the season points leader who won in Toronto in 2007 and 2010, said he wasn't aware the two had touched. And if they had contact, Power said, that's the nature of a course that features risks at every turn.

"It's a long straightaway with a breaking zone in Turn 3, which entices all the people to pass, which is good," Power said. "No one wants to see a procession. And Turn 1 a little bit like that, too, so that's what creates all the mayhem at this place."

Friday morning's practice session was marred by a frightening crash on pit lane that had nothing to do with the track. Justin Wilson blamed a transmission problem that led him to crash into the back of Bourdais' parked car. Two of Bourdais' crew members were treated and released from a hospital.

Wilson was involved in two more crashes, both in Turn 8.

With qualifying set for Saturday, there's plenty on the line, and numerous subplots as the IndyCar series heads into the final six-race stretch of its season.

Power faces questions of whether he can regain the momentum he had in winning three of the first four races of the year, all on street or road courses. His lead has dwindled to three points ahead of hard-charging Ryan Hunter-Reay, who is coming off oval wins at Milwaukee and Iowa.

Hometown favorite James Hinchcliffe has suddenly hit a setback. He will be penalized 10 spots on the starting grid after being forced to switch engines Friday.

Scott Dixon, who's in third place, says he spent the week off stewing over losing ground in the standings, and being on his last IndyCar approved engine.

And let's not forget the on-track exchange of profane gestures that took place between Power and E.J. Viso after the two wrecked two weeks ago at Iowa. Viso grabbed his crotch in response to Power making a vulgar gesture at him.

"I definitely wasn't happy, and on top of that I get that reaction from him after he took me out," Viso said. "I actually feel pretty good that I didn't do anything else."

Both drivers said they've patched up their differences.

It's been an up-and-down season for IndyCar. It enjoyed dramatic finishes at the Indy 500 and at Texas, and yet it also has endured its share of troubles.

The track at Belle Isle, Mich., was crumbling. A race scheduled to take place in China in August has been canceled.

And then there's what happened in Milwaukee, when IndyCar acknowledged it made a mistake in penalizing Dixon, which led to him finishing 11th.

Dixon has moved past that. Looking forward, he noted the way the season has gone for most everyone, anything is still possible given how 40 points separate the top six drivers.

"It's been kind of strange," Dixon said. "If you look at it, it looks like a championship nobody wants to win at the moment."