I live in a pretty rural area and have head to deal with mice, rats, and chipmunks in my T100 pickup and my partner's Honda CR-V. For me, putting my hood up hasn't made much of a difference; at best, it seems that it lets me look at the window and see the creatures running around in the engine compartment. I've had to replace blower motors on my T100 (it is pretty much impossible to block their access to the blower and vents on a T100) and my partner had her almost new CR-V go to Honda because the rats chewed up her wiring (i'm guessing we've had about $700 in damages so far from rodents this year). My point is, you might want to take more aggressive action than just putting up the hood, as they can quickly cause a lot of damage. We've had decent success with spraying peppermint oil but it needs to be done often. That said, please don't use poison, not only can that cause a creature to die in an inaccessible place and cause your vehicle to stink, it can also many other animals who would feed on a dead rodent (dogs, cats, birds, coyotes, foxes, etc.).
