I ask, why make announcements, why ask questions? Sure, everyone needs a warning of something they'll have to do soon. A fifteen-minute warning, a ten-minute warning and a five-minute warning works wonders. Just matter-of-fact statements about what's going to happen so that everyone knows.
But when the time comes, it's best just to go ahead and start the process-- start putting away the toys, putting on the shoes, taking his hand and leading him to the car-- whatever it is that needs to be done, even with a fun challenge attached like "ok, let's see if we can get in the car in 10 seconds." This way, the child is not put in the position of approving of anything, or disapproving-- it's simply what is happening, and he already knows about it from the warnings.
Try it and let me know what happens.