When they searched his British registered Peugeot tests showed that a yellow liquid in the windscreen washer bottle contained amphetamine.
Prokop told investigators from the National Crime Agency that he collected the drugs in Belgium and was due to deliver them to a location in Birmingham, where he would be paid around £2,000.
Prokop later admitted a charge of attempting to import a controlled drug and at a hearing at Canterbury Crown Court on Friday 22 November he was sentenced to three years and four months in prison.
He faces deportation after serving his sentence.
Malcolm Bragg, from the NCA's Border Policing Command, said: "This was a clever concealment involving a considerable amount of drugs. It demonstrates the lengths some criminal groups will go to in an effort to avoid detection.
"The NCA is determined to tackle those responsible for trafficking illegal substances into the UK and we are working with our Border Force colleagues to stay one step ahead of the smugglers."
Paul Morgan, Director of Border Force South, said: "This was an excellent detection of what was quite an unusual attempt to circumvent border controls, and is testament to the vigilance and expertise of Border Force officers.
"Working alongside our NCA colleagues we will continue to work hard to keep our borders safe and crack down on drug smuggling."
The NCA is a new law enforcement agency that has been tasked with leading the UK's fight to cut serious and organised crime.
It has over 300 border investigators at major ports, investigating detections of drugs, firearms, cash and other non-fiscal crime made by Border Force. The BPC also has an extensive overseas network of around 120 officers in 40 locations around the world.
