The actor, who hit screens on Tuesday in the BBC drama, reckons he shelled out 1,500 US dollars in fines on a total of five speeding tickets while powering through Europe in the Gumball 3,000 Rally.
Despite suffering from an injured foot, Idris is sharing the driving of an Aston Martin DB9 in the event, which sees 120 super cars drive on public roads from London to New York.
Speaking after his team's latest penalty, in Sweden, he said: "We were only going 130 miles an hour, but I'm not going to lie, we definitely came here wanting to win. It's not a race, it's a rally, but what we wanted to do was come in with impressive checking times."
The most recent fine came as Idris's co-driver was at the wheel and they were attempting to race against US rapper Xzibit, who is also taking part in the rally.
Idris said: "Xzibit got caught, and who knew we shouldn't stop to make sure he was all right? Once he got caught we pulled over like good Samaritans and they gave us a ticket for that! It was 150 Euros."
The British-born star said the only place he avoided being stopped was London, adding: "But I know my way around the streets and I know the hotspots."
The actor, who rose to fame as drugs baron Stringer Bell in US drama The Wire, also revealed his frustration at having to swap the car for a coach as they travelled through Germany, the one country on the route where the rally's drivers were not permitted to take to the road.
"It's so hypocritical because they've got no speed limits. It's not fair," he said. "It felt like being on a school trip when you're a kid."
US singer Eve, skateboard star Tony Hawk and jewellery designer Jade Jagger are among the other celebrities taking part in the event, which Idris said had won him 150 new friends.