AS-1 Auto Sleeve - Protects Your Customer's Window Glass
The Auto Sleeve is a super inexpensive way to protect the window glass and the weather stripping of the vehicle you are attempting to open using car opening tools. The tool is slipped through the sleeve, which is inserted between glass and weather stripping beforehand.
You can buy all sorts of wedges and air wedges to make it just a bit less risky when it comes to prying against a car's glass window, but even after you successfully get the wedge in place and create a gap you still have to insert the tool. I've used rags in the past to make a make-shift sheath for the car opening tool (slim jim or horizontal rod tool) - but here's a ridiculously inexpensive tool that is quick to use and easy to store. You oughta have a dozen of these on hand!