A while ago (like 10+ years) I read a book that I can't remember the name of. See if you can help.
- Took place in Europe
- Main character was a boy preteen or teen...he was later joined by a girl around his age
- He was extremely interested in WW2 memorabilia
- Somehow he & the girl travel back in time & get to meet Elvis (I want to say they got in an old humvee with some crystals in it....)
- There was a bad guy, but I honestly don't remember what he was after... something the boy had that could bring him to his proper time (some sort of magic crystals I think...)
- He ended up blowing himself up somehow & waking up in his own time period.
I know this is very vague but it's been a while. I feel like the name is on the tip of my tongue but can't for the life of me remember it.