This is our first winter with our new '99 Civic. During this past summer we were getting between 32 - 39mpg and really liking it. As soon as the weather turned cold the performance fell to around 26mpg. I have heard that because of the high precision nature of the Civic engines that cold weather alone can effect the performance quite a bit. (I used to drive an '82 Volvo and had no cold weather issues at all.) But could cold weather cause this much drop?
It was also suggested to me that the performance could be due to build-up in the injectors, and that again, because of the nature of the Civic engine it is especially vulnerable to this. If this is the case what is the recommended treatment. Is it enough to simply pour some injector cleaner in the tank? or is there a certain treatment/remedy that is best for the Civic in these conditions?