Vehicles still come with their own sensor suites. So they will be able to detect other vehicles, even if they have their wireless disabled. The car in front of you isn't broadcasting but you can still tell there's a car in front of you.
However, even in modern day, cops will pull you over if you're driving in the dark without headlights. I could imagine that especially for police, that wireless on your car is probably sending out license, registration, insurance, current speed, approximate tire wear, last oil change, and favorite radio station. When they see you drive by with your wireless completely disabled to the point if they query your vehicle in particular they still don't get a response, it would be akin to driving without a license plate and with the headlights turned off. As much as you're hoping not to be noticed, you're actually sticking out like a sore thumb.