Bought it new in Oct 2017; have 67K miles (covid and retirement reduced its mileage) on it. Originally got 42-45 mpg; after 2-3 years, started the car one morning (we don't have winter in South Central Texas, so I don't think the poor mileage is due to cold weather), it shuddered and quit (never did that before or after); since that time it has gotten 35-37 mpg. Except about 4-5 months ago, it shuddered and quit again, and after that it got 40-42 mpg for a month or two. Then I was driving one day, and the engine didn't turn off at stops or when coasting, as it usually did; it felt like an old fashioned transmission had shifted to low gear. Took it to the dealer, but of course it didn't have the symptoms then. Now back to getting 35-37 mpg. Any thoughts? Dealer says the computer indicates the engine is fine. I don't trust computers. I wish mechanics had to rely more on their experience and less on the computers to tell how a car is running!
Were diagnostic tools used? Programs, scanners? Imagine that you came to the hospital and said that you have a problem, but you don’t know what it is. You are sent for tests, an X-ray is taken, after which you are given an approximate diagnosis and prescribed medication for the disease. It’s about the same with a car.