The US version doesn't have a story yet, but the Japanese version's background is this: Autobot City is jsut finished when the Decepticons implement a blockade to keep them from Cybertron. Once that was in place, the Decepticons infected some Autobots with COsmic Rust, thus they need to be rebuilt by human car companies.

Basically these are G1 figures rebuilt with modern engineering, and modeled after real cars and such in 1:24 scale.