Dark parts on the car (Grand Theft Auto: San Andreas)

Hello everyone! Faced such a problem - I made a model of a car, made a UV scan with original textures, used materials from the original transport from the game. However, in the game itself there are, if I may say, problems with shading. For some reason, part of the hood, doors, some of the body and the rear bumper have a darker part than the rest of the parts. I'll tell you right away - It is very unlikely that this is a texture, since I double-checked everything, and all the UVs lie on one light part of the texture, as it should. The material is also used alone. Please help me what's the matter! Thank you in advance.