The method that the perpetrator used to set up that assassination attempt was like this,
If the driver failed to run them into the tanker and kill them in the explosion, he would explode while they were taking him to get interrogated and if lucky, he would finally get to kill them with that method.
And even if he did succeed, there was the bomb implanted in the car to make sure there was no single evidence left of the manipulated brakes.
That way, the investigators would never know how they died and that would close the case right away.
"I said I'm fine." Valerie said for the fifth time while they were on their way to Stewart's mansion.
"I'm not convinced." Max said. He held on to her hand and watched her closely, fearing that she wasn't okay, as she claimed.