But that's exactly what the tracking device he'd installed in the car reported back to him – within minutes of the car being collected from his home in Berkshire.
Brown arranged for the BMW to be collected through Servicing Stop, an online service previously featured on Dragons' Den, which sub-contracts repairs out to local companies.
The car was picked up by a mechanic from Karcare Services Ltd, an independent firm based in Reading.
Shortly afterwards, the TrackYourGPS device that Gary had installed in the car in case of theft sent him a text message to tell him that the car had broken the speed limit.
Brown told the Daily Mail: "I can't believe how irresponsibly someone was driving my car – especially because they knew it needed new brakes.
"It was so dangerous – the car might not have been able to stop quickly at such high speeds."
A spokesman for Servicing Stop said: "Servicing Stop are aware of an incident on the November 7 whereby a member of staff from a sub-contracted garage exceeded the relevant speed limit in a clients' vehicle, such circumstances are unacceptable and after considering our audit teams findings we have undertaken a disciplinary action against the garage in question.
"Alongside this our audit team have presented control recommendations which will be implemented as we look to ensure that Servicing Stop protect our clients and provide them with the quality of service we all expect.
"Whilst we are confident that the scheduled works on the vehicle were completed to the standards expected, this does not detract from the severity of this case and we are sympathetic to the distress and inconvenience this matter has caused our client."
Karcare Services declined to comment.