I have a Garmin Legend HCX with color Screen topo all that good stuff. Its a waterproof handheld. Its great for the quad and hunting but not so hot for the Hummer.
I would recommend the Garmin Nuvi 500. I had my hands on one this weekend offroad and it was awesome. Its perfect for a Truck. It has detailed topo and does street nav as well.
https://buy.garmin.com/shop/shop.do?pID=13424&ra=true