When I spotted the twin Hummers at a red light, I strolled up to the first truck and had a quick chat with the driver. Apparently, these are GM demonstration vehicles, and they were being ferried from one event to another. The driver told me the trucks were in off-road mode, with their height-adjustable suspensions in their tallest setting. I’m six feet tall, and standing by the front wheel, the hood was a little too high for me to comfortably rest my elbow on it. Like I said: huge.