The tarmac at the Auto City Speedway in Clio might not have ever witnessed such a slow-moving pace as it did on Saturday.

And that smell burning on the racetracks?

Certainly wasn’t gasoline.

It was smoke that filled the air as visitors to the fourth Midwest Cannabis Cup sparked up and sampled different strains of medical marijuana at the dozens of vendor tents, organized by High Times magazine.

The event began on Saturday and will run through Sunday. It features seminars on topics such as how to grow cup-winning cannabis; musical acts including 50 Cent, Wu-Tang Clan and Detroit rapper Danny Brown, and culinary samplings such as the an Italian cooking competition using bud-infused ingredients.

For Natalie and Nate Shafou, the occasion gave them the opportunity for a brother-sister outing and the chance to finally get their medical marijuana cards, which were being issued at a tent near the entrance to the festival.

The siblings, who made the road trip from metro Detroit, said that their mother knew about their plans and that she’s the one who has been telling them to get a card.

Nate Shafou said his mother and grandmother both have multiple sclerosis, and that they both carry medical marijuana cards.

“It helps them,” he said. “And we both have scoliosis, so we’re just trying to seek alternative methods for our pain.”

James Wheeler, 24, and Ariana Williams, 27, of Colon — or, the “magic capital of the world,” as they call it — both already have their medical marijuana cards but said one of the reasons they were at the festival was to learn more about the legality of carrying one, because they would like to remain on “the good side of the rules.”

Wheeler and Williams, who were puffing on a joint and eating a mint chocolate edible they bought from the festival, said they only smoke at home, and that there was less anxiety at the festival, where they were smoking openly under a tent.

“It’s a chill thing to do, so when it gets all stressful — it being illegal and whatnot — it’s nice to just smoke and not have to worry about anyone getting you in trouble,” Wheeler said.

But not everyone was there for a smoke or a card.

Germane Scott, 43, and Cleatrice Jones, 39, of Detroit both haven’t smoked in some time — Scott in eight months and Jones in about three months. Both have abstained due to employment reasons. Scott has to pass a hair test coming up in a couple of months, and Jones is preparing for a new job in sales, where she said they’ll be testing.

Scott, whom Jones described as having a green thumb, said he was at the Cannabis Cup to check out the seed vendors and “go home with some nice genetics.”

Scott said that he was teasing himself by being there, but that if he could abstain at the Cannabis Cup, then he could do it anywhere.

“I’ve got something better waiting for me. Once I cross that hump, then I’ll be able to indulge, but as for now, I can’t,” Scott said. “I’m getting weak by some of the smells.”