Officers said they had followed the motorist last weekend as he raced along the M18, having been clocked doing 35mph above the national speed limit by a marked car.
South Yorkshire Police's Operational Support Unit said the man didn't appear to notice the BMW 530 traffic car trailing him, meaning he can't have checked his mirrors for 'some distance'.
Eventually, however, the driver was pulled over by officers, who asked why he was travelling at such a high speed.
The man told cops he was 'desperate for the toilet', having driven up from London - but his excuse didn't seem to go down too well with police, who noticed he was able to sit down 'quite comfortably' with them to have a chat.
In a post to Facebook, a spokesman for SYP's Operational Support Unit said: "The bit of kit in the picture is in one of our marked cars.
"The reading on the bit of kit came about when said marked car followed another vehicle along the M18 last weekend.
"As much as we would sometimes love to have a cloaking device in our cars, we didn't need it for this chap.
"Our BMW 530, in high-vis Battenberg, was able to follow him for some distance without him checking his mirrors and seeing we were there.
"The driver's excuse? He was desperate for the toilet having driven all the way up from London."
One Facebook user commented: "There are some complete idiots out there."
Quoting the statement, another joked: "'Didn't check his mirrors'. Was he driving a BMW too?"
A third added: "The law is the law. 70 mph. Stick to it."
The force said the driver was 'off to court' to face speeding charges, adding: "Despite his desperation, he seemed able enough to sit with us quite comfortably for ten minutes while our colleague broke out his pen and spoiled some paper."
Without trying to sound like someone's mum, just make sure you go for a wee before you head on the road, eh? And if you find yourself caught out while travelling, there's always a service station you can pull into - you can even grab a box of Krispy Kremes while you're at it, so it's a win-win really...
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