Wait until you see the new Tacoma. The lowest spot is the driver side exhaust as it crosses over. It could cross the frame in a dozen places, but for some reason, they ran it behind the t-case, and squished it into an egg shape for more clearance. It hangs more than an inch lower than the rest of the truck waiting to get nailed by a rock.

The new Frontier (and Xterra) are dead flat across the entire underside, very cool and well designed.

I've owned a 4Runner and am very familiar with them. Stock for stock there is very little difference between it and the Xterra for ground clearance. The rear diff on the Toyota is smaller than the Nissan, so their diff will have a bit more clearance, but that is governed only by tire size.

The front lower control arms are a different design offering more clearance due to how they contain the lower ball joint of the spindle. By doing that, they give the illusion of being angled downward like a lifted Nissan, but the front crossmember is within half an inch of the Xterra.