As you'll see, the design is a bit more alien-organic, with terminators more alluded to through part design than outright placed, doggy-style, on two wheels.
This and other Terminator: Salvation concept art can be seen in The Art of Terminator Salvation by Titan Books. We just hope that editors were kind enough to omit the rear angle shot. There are anatomical facts about terminators that we just don't need to know.