My Dad has the ivory interior in his '03, I've got the charcoal in my '05....

I recall when my Dad bought his car in '03, the salesman told us that they only made the Hybrids using light exterior and interior colors, so they would stay cooler and wouldn't tax the A/C system. In '04 Honda made the HCH available with darker exterior and interior colors. I'm not sure if the salesman was BSing us, but it made sense, having said that and having a magnesium HCH with the charcoal interior, I prefer the lighter ivory interior based on the fact that it's easier on the A/C in the summer.