[Grantaire would honestly not be surprised if that happened, though it would be a crying shame, thus, why he's taken it upon himself to convince Enjolras to please get some sleep and let him drive.]

There are ropes, you can use those to tie yourself to the backseat. [He should know, he's done that more than once. Besides, what's life without a little risk?] Four hours of sleep while I drive will not, contrary to what you may think, kill us both. In fact, you'll find it much more beneficial to your health as opposed to, say, drinking can after can of Red Bull.

[And he isn't that drunk, he's most certainly not going to crash Dionysus into a lamp post or something if he takes the wheel. He likes his truck too much to do that.]