Dale Lyle, 21, of Staple Hill, spent £1,200 proving his innocence after his L-reg 1.3 litre Honda Civic was clocked by a mobile speed camera.
He contested the accusation in court and magistrates challenged him to "prove it".
So Mr Lyle, who had sold the 14-year-old car, bought it back for £600 and paid an independent driving expert £600 to take it on a two-mile test circuit at top speed.
The results showed that even when driven flat-out the Honda could only do 85.4mph in fourth gear and 81.3mph in fifth.
Mr Lyle, a financial worker, who has a clean licence, was cleared of speeding after he presented his evidence in court.
He now intends to return to court to ask magistrates to award him £1,200 compensation to cover his costs.
He said: "The whole thing has been a complete shambles and waste of money. It's shocking how hard it has been for me to prove my innocence.
"I was in total disbelief when I opened the letter because I've never driven my car over the speed limit, let alone at 98mph.
"It's such a small car I wouldn't feel safe - it's a glorified Japanese shopping trolley.
"I told the magistrates 'I'm not being funny but this car is ancient and has 130,000 miles on the clock - there's no way it will do that speed'.
"I was very nervous and my heart was going 90 to dozen but they just turned around to me and said 'prove it'. So I did.''
Mr Lyle was accused of speeding at 98mph on a 70mph three-lane carriageway of the A38 near Plymouth, on December 13, 2007.
He immediately pleaded not guilty and was ordered to appear in court in June last year.
But Mr Lyle had already sold the red Civic to a friend and had to take out a bank overdraft to buy it back for £600.
He then shelled out a further £600 to have it speed tested at a circuit in Bedfordshire.
Mr Lyle also obtained the mobile speed camera footage of his alleged offence from the Crown Prosecution Service (CPS), which showed another car in the same frame when the camera claimed his car was doing 98mph.
He added: "When the three-minute film starts the mobile speed camera is panning into the sky, then it focuses on the middle lane but it doesn't take any readings.
"Then you see the operator point the camera at me as I pull out into the third lane, but cars on the inside lanes obstruct the view.
"When the 98mph reading flashes up there is another car in the picture - I think the camera must have confused the distance with the other car.
"It makes you wonder how many people say 'fine, give me the points' when they are not guilty."
Mr Lyle had been told he faced a maximum £1,000 fine and six-month ban.
A CPS spokesman said: "We came to the conclusion that there was no longer sufficient evidence to provide a prospect of a conviction.
"Recompense is a matter between the defendant and the court."