While I prefer a wounded rabbit mouth-blown call, I've used a baby boom-box with wounded rabbit tapes to good effect.
Our coyotes around here aren't hunted often, so just setting the box on the hood of the truck works fine.
Haven't had one jump up on the truck, yet.
Although, some guys out calling one night had a mountain lion jump into the back of the truck and reach in through the rear window of the cab.
New upholstery.
Art