How To
John Paul, AAA Northeast’s Car Doctor, hears from a reader experiencing a vibration when driving their Dodge Challenger a certain way.
Q. I just bought a 2023 Dodge Challenger R/T 5.7 Hemi with only 1,700 miles. When I am driving in normal mode at a steady speed at around 40-50 miles per hour and I give it a little gas, there is a vibration from the exhaust. When I switch to sport mode it is better. Is this normal?
A. Your 5.7-liter Hemi powered Challenger may have the dual-chamber exhaust. At low speeds or in normal mode, the exhaust is being restricted slightly. In sport mode there is less restriction. Also in sport mode the shift points are different. The combination of the slightly restricted exhaust and more economical shift points could cause a very slight vibration and would be considered normal.
Q. I have a 2012 Toyota Camry SE with 43,000 miles. It has never been serviced outside of a Toyota dealership, and I have every receipt to show it. The last service was in July for an oil change and tire sensor issue. Lately, I feel like when I go get it serviced; my car gets pushed aside because it is old. I also brought this feeling up in January at my inspection that there was a problem with the tire sensor. At the time they said it was fine, only to have it replaced in July. I have always put my trust in Toyota, but I have doubts now. Do you think it is time to give up the dealership for a respectable repair shop? Any information you can give me would be greatly appreciated.
A. At 13, almost 14 years old, the dealership may not have readily available parts, which could make it seem like the service department is pushing your car aside to work on cars that are newer and under warranty. Could you go to an independent shop? Certainly. Can an independent shop provide the same level of service that you once were used to at the dealer? Yes. See a list of AAA approved shops here.
Q. You always say you answer every question, so I have two on my 2021 Mazda CX-5. When I start the car and turn on the heat, regardless of what vent(s) I use, the car makes a high-pitch cricket-sounding noise from the right side. But after a few minutes the sound goes away. The heat seems to operate properly, and it is quiet when the air conditioner is first turned on. The second question, a couple of times the infotainment screen has gone blank, but the radio will still play. When this happens the screen stays blank. But the next time I start the car, the screen operates properly. Any thoughts?
A. The climate control system uses motors to operate the temperature blend door and air distribution. I suspect the motor for the temperature blend door is failing or sticking, causing a creaking when trying to operate. As for the infotainment screen, many Mazda vehicles have had a failure of the touch screen, causing the screen to go blank or change on its own. There was even a class action lawsuit on 2016-2020 model CX-5s. Perhaps the issue carried over to later years. And yes, I answer every email.
Q. I have a 2020 Mercedes GLE 350 with the four-cylinder turbo-charged engine. I purchased it new and it runs great. I have not had any issues at all, and it currently has 36,000 miles. The gas cap calls for 91 octane gasoline, but I have used 87 octane gas from Day One. The gas mileage is fine, around town about 18-20 miles per gallon and 24-25 miles per gallon on trips. One individual at Mercedes told me to use 87 octane and another told me 91 octane. Who is correct? Also, I plan to keep this car for 10 years, should I consider adding an additive on occasion like Chevron Techron, or do nothing?
A. Whenever I am in doubt I go to the vehicle owner’s manual (most are online). Mercedes states to get maximum performance and fuel economy use 91 octane fuel. If you are satisfied with the performance and miles per gallon, keep using the 87 octane. Mercedes does caution not to use gasoline with less than 87 octane. Also, Mercedes is pretty specific about ethanol fuel. Mercedes-Benz owner’s manuals clearly state that gasoline with more than 10% ethanol, such as E15, is prohibited for use in their vehicles. As for a fuel additive once or twice per year adding Techron is fine and something I do in my own vehicles.
Reader comment: Last week’s column generated a bit of disagreement on fully charging an electric vehicle battery. One reader commented “Volvo recommends charging to 90%, but no one thinks you should go to 100%.” The reader also pointed out that most batteries are never really charged to 100%, the manufacturer always leaves some space. As an example the Hyundai mentioned never fills more than 95.6%. I certainly agree to maximize battery life, a daily charge to 80-90 percent is best. Fully charging an EV battery can reduce its long-term life. So, if we are facing single-digit cold, some manufacturers will recommend charging to 100 percent, but also advise you to drive the car soon after. Don’t let the battery sit at 100 percent for hours/days. So the bottom line, when in doubt, read the owner’s manual.
John Paul is AAA Northeast’s Car Doctor. He has over 40 years of experience in the automotive business and is an ASE-certified master technician. E-mail your Car Doctor question to [email protected]. Listen to the Car Doctor podcast at johnfpaul.podbean.com.
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