The inquest heard Mr Gandhi, the director of Rehncy Shaheem Chartered Accountants, in Greenford, west London, told the male police call handler: "My car is not coming out of the cruise control.
"I have just passed the exit of the M40 towards Slough. It is not letting me stop. It [the speedometer] shows 70mph, but I think I am going much faster than this."
The call handler from Thames Valley Police asked: "Can you slow to a stop by braking? Can you try to control the car's speed using your gears?"
"I am trying. It is not stopping at neutral," said Mr Gandhi, before a faint beep could be heard as he tried turning off his engine by pressing the start-stop button.
"I have kept pressing the button, but all it makes is a noise," he said. "My speed is increasing. I think what has happened was I tried to change the mode on the car, because I was on the sports mode. I pressed a button to come onto the normal mode and then it is not allowing me to do anything."