There's an El Camino (or is that Caballero?) version of the GMC Granite Concept. It's called the Granite CPU, it has an expandable bed, and no one's seen until now. First photos of the GMC Granamino below.
Not unlike the GMC granite itself, the Compact Pickup (CPU) is only "professional grade" if you're an urban professional. But unlike the original Granite, which is more of a social vehicle than a functional weekend hauler, the CPU's ready to carry an entire Ikea's worth of kitchen furniture.
Though smaller than the Terrain by a full two feet, the CPU's tiny approximately four-foot bed suddenly transforms into a useful space for transporting objects up to six-feet long. The clever design sees the rear split-gate spread out while the rear slides out. There's even taillights built into the gate so you can legally drive it that way.
Finally, if you need even more room to haul lumber or a surfboard, a "pack rack" roll bar pops up and out. Both useful and attractive, it's no surprise GM's kept it hidden for so long.