Q. I have a 2015 Kia Optima with 66,000 miles on it which has had all its recommended maintenance by a dealership.  It drives really well except in one respect.  At slower speeds in city driving, I experience a noticeable engine vibration that is sustained whenever the tachometer remains very narrowly at or close to 1100 RPMs.  It feels like the engine is lugging, if that’s the correct term.  It relents only if I let up on the gas or depress the pedal further to accelerate past the vibrating.  In other words, I can’t maintain a steady speed at 1100 RPM without the shake.  I actually did mention this to the dealership at my 60,000-mile service, but they did nothing to diagnose it and I didn’t pursue it further.  What do you think could be causing this? 

A. I would go back to the dealer and have them check for transmission codes. What you are describing sounds like the transmission torque convertor is staying locked up, this is sometimes called “chuggle”. Kia did come out with an update to a part called a damper clutch solenoid which may cure the issue. In addition, this could also be a combination of the transmission design and the beginning of a very slight engine misfire. At 66,000 miles if one of the spark plugs is getting a bit worn, this could also exaggerate the condition. 

Q. Several weeks ago, my 17-year-old son, purchased a car for $4500.  The car, a BMW, actually seemed to be a good deal, but he then returned to the same seller in the hope of getting a different color. The second car turned out to have a fraudulent title as well as an odometer that had been turned back. We discovered this through a Carfax report. I was informed by both my son and his mother that they attempted to get even some of their money back and return the car, but the seller refused and at this point may have actually even blocked their phone numbers. Do you have any suggestions as to how we might proceed to rectify this issue/problem?

A. The first thing that needs to be determined is if the seller was a legitimate car dealer or someone who just buys and sells cars without a license. The seller may be someone who just “jumps” titles selling a car they purchased without re-titling it in their name. Depending on where you live, state agencies rarely get involved in private party sales.  If they are a legitimate car dealer you may be able to get some help through a dealer organization or the Attorney General in your state. Odometer and title fraud are subject to both state and federal laws and can carry serious fines. At this point you may need to contact an attorney that specializes in automobile fraud.  

Q. I have a 2006 Ford Mustang convertible which is in great condition but makes a clunking noise which can’t be located. I have had the car checked over, but all the parts seem to be in good shape. 

A. I would take one more look at all of the suspension components including the front struts and strut bearings. At 16 years old there could also be some wear in the steering column. Your Mustang like many cars uses two flexible joints that connect the steering column to the rack and pinion steer gear. If one of this joints is worn, there will be a clunk. 

Q. I have a 2008 Toyota Prius with 155,000 miles on it. It is in good condition for its age, but it will need a catalytic converter. The car drives fine, it is just noisy.  Any idea how much I should ask for the car and where I should list it for sale? 

A. I would list the car in www.cargurus.com, www.iseecars.com and even Facebook marketplace. Determining the price is a little tricky. The going price for this model is $7000-$9000 depending on condition. I’m sure you have a price on a new exhaust and catalytic converter, which can cost up to $2500 depending on where you take the car for service.  I would scan the ads on Cargurus, Iseecars and other websites and try to find a match to your car and price it accordingly. My guess is around $6500 is about right but used car prices are still crazy. What makes this car a bit less desirable is with any used hybrid potential buyers are going to be concerned about the hybrid battery life. Although the buyer may be willing to take a chance on a car that gets 50 miles per gallon. 

John Paul is AAA Northeast’s Car Doctor. He has over forty years’ experience and is an ASE-certified master technician. He will answer readers’ questions each week. Email your car questions to [email protected]. Follow John on Twitter @johnfpaul and friend him on Facebook, mrjohnfpaul.