According to Leon's orders, his men's cars indeed followed Susan Parkinson's car but the difference was his men were unconscious or powerless lying in the trunk of the car.
The Rivas security men drove the car leisurely taking their own time. They were just pretending as Leon's orders were being followed but in reality, Susan's car security increased more.
After the so-called 'Missing the target' repetition, there was only one last attack location left. Susan's car driver drove the car without being aware of how many people were ready to kill him just to reach Susan.
Aarvi knew she could have done the same thing with Susan in the car but that would be underestimating Leon and she wasn't ready to take any chances with her life.
So why not being double careful?
Have some idea about my story? Comment it and let me know.
Much Love,
Munchkin