Am starting to think of trying some mods to see if I can increase gas mileage and would love some feedback. Does changing the air filter to a K&N high performance filter really improve mileage? Would an entire airflow kit work better? As it is my standard air filter is amazingly clean even after 9 months of use so I'm not sure what the deal is. Am I getting enough air flow currently? I know it's an odd question but the fact that the air filter is so clean still just seems weird. Got 40,000 on the current set of spark plugs but they are pretty clean and not fouled at all so not sure they are a problem. Could change them out but I do it in Fall regularly. Do new plugs really make a difference as I haven't noticed any problems this past year? Also, my idle seems a bit high but I don't know that I want to mess with it as there is no problem with "coughing" or sputtering or stalling and lurching. Don't really want to "fix" something if it's working good but would lowering the idle make a noticeable difference in gas consumption? Is there such a thing as a broken thermostat that affects cooling? Meaning, my gauge has dropped to below C for cold so I don't know if it's a broken gauge or if the thermostat is messed up. I'm used to thermostat issues having to do with overheating so I'm confused on this one. The water pump (knock wood) seems fine. Thanks much to anyone who has advice.