I recommend: Deluxe highway emergency kits (which include tools, flares and jumper cables), safety lanterns, auto cleaning kits and deluxe first aid kits (complete with tourniquets, gauze, splints and bandages with clips) make excellent thank you gifts.
When you hand your promotional safety gift to your customer, be sure to shake his or her hand and give a warm and personal thank you. The gift, plus a personal touch will give your customers even more reasons to remember your name in the future.