Kevin Gordon claimed he used his cruise control to avoid speeding but had not noticed he was driving though a residential area.
Gordon, who works for Peter Vardy, was clocked driving at 59mph in a 30mph limit, but begged a court not to ban him as it would have a "catastrophic" effect on him.
The salesman, who already had three points on his licence, claimed he used the speed limiting device on his car at all times because he needed his licence.
Solicitor Grant Bruce, defending, told Perth Justice of the Peace Court: "His licence is crucial to him because of the job he does.
"He is a sales manager which involves him driving round auctions around the country. He was travelling into Coupar Angus at around 60mph and he uses cruise control.
"He had it on to make sure he wasn't exceeding the speed limit. He switched off the cruise control and started to reduce speed to what he thought was the 30mph limit."
Gordon, 37, Priory Wynd, Forfar, admitted speeding at 59mph in his Vauxhall Antara on the A94 Forfar to Coupar Angus road on January 7 this year.
Justice of the Peace Eve Forrest said she would normally have banned anyone driving at that speed, but said: "I am going to give you six points, which will leave nine points on your licence and should be a greater deterrent than taking you off the road for a few weeks."
Gordon was fined £440.