David Pickup was caught speeding and has to pay £11,000 for challenging his ticket after a prosecution expert hired an airfield and a sports car to prove him wrong.
Flintshire Magistrates' Court heard a police speed camera caught him and he asked officers: "Can we call it 98?".
Mr Pickup who is from Wilmslow in Cheshire, who has a holiday home in Abersoch, Gwynedd, was convicted of speeding.
He denied breaking the 70mph speed limit and said that a number of people from Cheshire had second homes in Abersoch, which he called a millionaire's paradise.
The defence questioned the accuracy of the in-car police speed camera so the prosecution hired an expert who rented an airfield and an Audi R8 to carry out tests, the results of which were presented to the court.
Pickup was fined £675, given six points on his licence and ordered to pay the full prosecution costs - which included the testing - of £10,384.