Even if Shiro would have been brought back less than a week later, Rin wasn't like that at all. Plus the condition of the truck probably wouldn't even kill a person at that speed. Just... slightly maim them.

Rin raised an eyebrow at that, and at the turning, only slowing the truck enough that he wasn't moving forward much more than a few inches at a time.

"... you do realize you're not in Japan anymore, right? And you ain't goin' anywhere! There's a barrier around this whole area! If you touch it you're just gonna get a really nasty shock!"

And if you run in to it at ridiculous speeds you might just explode.

He's saving that explanation as a last resort.