A series of spot checks on cars with tinted windows is being launched in Devon on Friday.
Police say it is similar to wearing sunglasses at night
A similar operation last year found that most of the vehicles stopped had illegal tinting.
Regulations state windscreens must let in 75% of light, with 70% in a vehicle's side windows.
The operation by Plymouth traffic police at secret locations is being run in partnership with the Vehicle and Operator Services Agency (VOSA).
The officers from VOSA will have equipment capable of checking how much light gets through.
Some tinting is allowed but the law states there should be no restriction to a driver's ability to see the road.
Pc Ian Tanner said: "The use of vehicles with too much tinted glass causes problems for both the driver and other road users.
"The driver is effectively wearing a pair of sunglasses at night which severely restricts their vision.
"This reduces the ability to see other road users - most importantly pedestrians - at night."