A man accused of driving at 115mph on a motorway had the charges dropped when he proved his car was not capable of reaching such a speed.
Prosecutors dropped the speed charge after seeing the evidence
Steve Lucas, of St Helens, Merseyside, commissioned an independent speed survey from experts, whose evidence led a court to drop the speeding charge.
Law student Lucas, 20, was charged after driving his 1.2 litre Fiat Punto on the M62 in West Yorkshire.
He agreed he reached 85mph, but said the 115mph claim was "laughable".
If he had been convicted, Lucas faced a six-month driving ban and a fine of up to £2,500.
He commissioned an independent traffic consultant to put the car through its paces at Bruntingthorpe test track in Leicestershire, where it showed a top
speed of just 104mph.
Prosecutors at Pontefract Magistrates' Court dropped the speeding charge when they saw the expert evidence.
Mr Lucas pleaded guilty to a separate charge of driving without due care and attention, for which he received three penalty points and a £40 fine.
Following the case he said: "I was happy to put my hands up and admit that I was driving at 85mph.
"But the idea that my car could go 115mph was laughable. I decided to fight it on principle."
His solicitor, Sean Joyce, said drivers who feel they have been treated unfairly in this way should "stand up and challenge" the police.
He said: "There are hundreds of thousands of speeding tickets issued every year in this country and the vast majority of motorists simply lie down and
"This case shows that, if people feel strongly, as Mr Lucas did, that the police are wrong, they should stand up and challenge them in the courts.
"If they are successful, they can make an application for their defence costs to be reimbursed."
West Yorkshire Police declined to comment.