My car has a very-high (4-5k) rpm for highway driving at 55-60 mph ?

Hey, my name is Dusty, and I'm one of the auto experts on RepairPal's Car Genius team. I'm here to help! It sounds like there may be a few issues affecting your Camry's performance and fuel efficiency after you have had the alternator and serpentine belt changed. If the serpentine belt isn't routed correctly, it could cause unusual behavior. However, the symptoms you've described could also indicate a range of engine or transmission issues. A first-hand evaluation is the next step to pinpoint the exact cause. The sudden change in the displayed cruising distance after filling up could be due to resetting the average fuel economy calculation in your car's computer system. This could have happened during the alternator replacement, which would have required disconnecting the battery to protect the electrical systems. It could also be related to the fuel quality from the different gas stations. Given these issues and the change in performance after a recent repair, it's a good idea to get a second opinion. Always communicate concerns clearly and ask for a detailed diagnosis before any repairs. It's crucial to provide details of your previous experience so that professionals have all the facts. They'll be able to perform a thorough inspection to identify any potential issues with the alternator replacement, serpentine belt installation, or any related components that might be affecting your car's performance and fuel efficiency. This will help ensure that the root cause of the problems is properly addressed. If you have any other questions or would like help finding a RepairPal Certified shop in your area, call us! 877-913-1554