This question is just begging to be answered! I was just thinking about this earlier today...an answer must be found!
How do you say it?
350 Zed -vs- 350 Zee
240 Zed -vs- 240 Zee
300 ZedX -vs- 300 ZeeX
Camaro Zed-twenty-eight -vs- Camaro Zee-twenty-eight
Personally, all this "Zee" business sounds like rubbish to me, but all the Americans on here are probably saying the same thing about "Zed"
EDIT: Just for the record, the entire rest of the world says "Zed"... maybe "Zed" is metric