High Tech Misfit,
>
>> I have a '98 Odyssey EX. Over the last month or two, it has gone from
>> 25mpg highway to 20. It's nothing obvious like a disconnected spark
>> plug or an underinflated tire. Any guesses what it could be?
>
> Is it winter-like cold in your area? If so, that's probably why.

Can cold weather really cause a *20%* drop in fuel economy?