when i went to get insurance on my zx2 i was asked is it the hot or cool version. what is the diffrence between the two. also my zx2 has 151K and it seems to be getting 25 mpg on the highway. i have done a compleat fuelsystem cleaner changed the plugs (not because of the fuel consuption) and cleaned the airfilter(k+n filter). im kinda not worried about it but it would be nice to know why.