Okay, he was not expecting the truck to actually work, not after Rin had been kicking it and all. He was a little surprised that Rin hadn't just run him over, since that was what Shiro would have done if the situation had been reversed.

"Nope, sorry," Shiro shouted back over the sound of the engine, "I've got things to do with it."

Then he saw the partially collapsed area by the train tracks ahead, and he turned so he could head right towards it. He could hop over holes in the ground, but a truck couldn't drive over them.