Why vehicles drift from the center of the road even if the steer control is 0?

[shihabict]

Stuck in this issue for a long time, Sincerely asking help from the experts.

Setup:

CARLA version: 9.15
Platform: Ubuntu 22.04.5 LTS
Python version: 3.8
GPU: NVIDIA GeForce RTX 3060
GPU Drivers: 575.64.03

Screen Recording of the issue
Carla simulation

Opendrive Map

Describe the bug

I am new to Carla; during my simulation, the vehicles drift from the center of the road even if my steering angle is always set to zero. I need to keep them on the same line. When I spawn the vehicle, I set the y position to zero to place the car in the center of the road.

Observation: As the speed increases, the vehicles begin to drift, and the direction of the slide is not consistent.