How can I get the best gas mileage? | Car Doctor
Q: Gas is still too expensive. How do you get the best gas mileage driving in highway or local traffic conditions?
A: Start with basic preventive maintenance. Check the vehicle's tire pressure once a month and inflate the tires to the figure indicated on the tire pressure door placard.
If you have been lacking on preventive maintenance, such as spark plug and filter replacement, get those items taken care of.
If a check engine light is on, the problem that triggered the light could be affecting fuel mileage.
Finally, as the old adage says, going easy on the gas and brake maximizes fuel economy. Anytime you accelerate hard or brake hard you are wasting energy. Most cars will get the best fuel economy at 55 mph; exceeding the posted speed limit will waste fuel.
Q: My husband and I own a 2013 Dodge Grand Caravan. The check engine light comes on a lot lately after we fuel up. We “jiggle” the gas cap and it seems loose. It doesn’t tighten up much if we turn it often and hear the clicks.
If we have it in the “proper” place, the check engine light doesn’t come back on. Should we purchase a new OEM gas cap or flip the “O” ring on the old one?
By the way, why is it necessary to tighten the cap to three clicks? Why not two or four clicks?
A: It sounds like you did a great job of diagnosing the source of the check engine light. Although flipping the “O” ring may work, it would be best to buy a new gas cap. In this case, I would use only a factory Dodge gas cap. I have seen some aftermarket caps that just don’t seal as well as the OEM cap.
Regarding the number of clicks, years ago I asked a GM engineer that same question. Three was just an arbitrary number to get the gas cap tight.
Q: I have a 2018 Kia Soul, and the emission light has come on. I tried disconnecting the battery and the light is still on. I also needed to have some body work done to the front end. Is there a possible connection to the light being on and the body repair? Is it a simple fix or a mechanical issue?
A: The light is on because there is a fault. Disconnecting the battery would clear the fault but not solve the problem.
Start with checking for fault codes to determine where the issue is. Could it be the result of a sensor that was disconnected during the body repair? Absolutely.
Checking for codes and a doing a good visual inspection will help you determine the problem.
Q: I recently read your comments regarding snow tires versus all-season tires. I was wondering how all-terrain tires compare with snow tires during winter months in Massachusetts, my home state. My vehicle is a Chevy S10 LS short-bed, rear-wheel drive.
A: The more aggressive tread of the all-terrain tires will give you more traction in the snow.
Where dedicated winter tires will do a little better is in the cold weather. The rubber in winter tires is formulated to be “stickier” in cold weather than most tires.
Where your rear-wheel drive suffers a bit is the back end. Adding and securing a couple hundred pounds of weight over the rear axle can help improve traction.
Q: Reading the piece about timing belts makes me wonder whether replacing the very expensive timing chain system on my 2015 Volkswagen Tiguan was part of normal 120,000 maintenance or was otherwise part of a good preventive maintenance program? Or was this repair not necessary?
There were no signs of poor timing or chain wear, as far as I can tell. The service adviser did not say that was the case. If it turns out the timing chain did not need replacement, do you have any advice about how I should proceed?
A: Some Volkswagen engines did suffer from timing chain failure due to the tensioner and guides breaking. But as far as normal maintenance, there is no reason to replace a perfectly good timing chain just because of age. In the VW maintenance guide, there is no listing for timing chain maintenance. If the chain is sloppy, there usually will be a code for a crankshaft or camshaft sensor.
It sounds as if they did this for preventive maintenance. Since you agreed, I'm not sure there is much you can do. Is your VW better because of it? Yes. Was it needed? Maybe not.
John Paul is the AAA Northeast Car Doctor. He has more than 40 years of experience in the automobile industry and is an ASE-Certified Master Technician. Write to John Paul, The Car Doctor, at 110 Royal Little Drive, Providence, RI 02904. Or email jpaul@aaanortheast.com and put “Car Doctor” in the subject field. Follow him on Twitter @johnfpaul or on Facebook.
This article originally appeared on The Providence Journal: How can I get the best gas mileage? | Car Doctor
