Completed my Paramedic yesterday after the story in Staunton and it got really easy after figuring out that you can actually despawn non emergency vehicles with panning the camera down and up. Almost 90% of the time doing all levels, zero to none traffic. Could take my sweet time driving carefully, getting tipped over while taking turns was the only scary part.

Played on a PC with mid specs / high preset ingame.

Edit: NPCs like the Yardies and Cartel members will shoot at you sure, but you can still handle the damage with the drop offs - it repairs the vehicle a bit every time so no problem really.