Richard Thomas Clarke, 38, who appeared from custody, admitted driving at a speed dangerous to the public.
The court heard that it was 7.30pm on a Saturday when he was caught in a police speed check as he drove towards Pembroke with two passengers in the car.
When stopped by the police officer, he acknowledged the recorded speed and said he held only a provisional licence. In interview he said a friend had given him the rare opportunity to drive the car. This had been a wake-up call for him and he was aware that his actions had been dangerous.
He must pay more attention in future.
Advocate Samuel Steel said his client had only just bought the Renault Megane Sport and had been displaying L-plates on it.
He had not been sure how fast he was going and was shocked to discover the speed. He had an unenviable record, with offences mostly for drugs and dishonesty, and there were no motoring matters for 18 years.
Judge Graeme McKerrell said it had been a ludicrous speed to drive at.
The defendant had a bad record but there was nothing recent for motoring matters.
The court was told that the defendant was currently in prison for another matter and was not due for release until next summer.
He was fined £1,000 and banned from driving for 18 months. He must attend a fine review court on 30 August next year if it was not paid by then.