Sainsbury's and Tesco shoppers could face a fine when just "nipping in" to stores if they fail to adhere to parking rules.
The supermarkets are especially keeping an eye out for people parked in parent and child bays without actually having kids with them.
Sainsbury's "regularly monitors" its customer car parks and those parked in the wrong spot will have to pay a price, according to new research from Confused.com.
Parent and child bays are often a life-saver for those shopping with kids, allowing them a larger designated space to manoeuvre their little ones in and out of a car.
The bays give parents enough space to safely buckle their children into their car seats - or fold a pram or buggy, among other things.
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But they're often used by shoppers who don't need them, the new analysis by Confused.com found, reports the Liverpool Echo.
The most common excuse for customers misusing spaces on the bay is that they were just "nipping in" to the store for a few minutes - or because they couldn't find any other spaces.
Sainsbury's says it clearly signposts its parent and child bays to avoid this, but anyone found to be misusing them could be slapped with a parking ticket.
It is understood that people are also at risk of a Parking Charge Notice (PCN) if caught using these bays incorrectly at Tesco.
Since most supermarket car parks are on private property, there are no official government or council-level rules on these bays, which means it is not illegal to incorrectly park in them.
But supermarkets can still issue a PCN in the same way a parking attendant would if you were to overstay your welcome in a car park.
A parking charge notice on private property can cost as much as £100.
Other major supermarkets appear to be taking their parking rules just as seriously, with Asda customers at risk of a penalty charge when parked in the incorrect spot.
Asda’s car parks are monitored by an external agency who carry out regular checks to enforce their parking regulations.
But some supermarkets take a slightly more lenient approach to parking rules, according to Confused.com.
Customers who are found in the incorrect parking space at Morrisons are first politely asked to move, or will have a sign placed on their windscreens.
And while Lidl monitors the use of parent and child parking bays, they say that they strongly rely on the honesty of customers to park correctly.
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