Mercedes-Benz has unveiled the world’s first big rig that drives without a drop of fuel. The new Mercedes-Benz Urban eTruck has an electrically driven rear axle and is powered by three lithium-ion battery modules. The zero-emission vehicle has an admissible total weight of up to 26 tonnes with a range of 200 kilometers (124 miles). Although the range is on the low side, the model here is still a prototype. And, as Engadget pointed out,…