I have a 2014 C250. For the past few months, I was noticing that it was feeling sluggish. The gas pedal wasn't responding as quickly. I checked my levels, filled the tires to the max cold pressure, etc. Last week was my Service A and I asked them about resetting my chip. They said they talked to the mechanic and he didn't know what exactly I was referring to.

Anyways, since the service, my car is noticeably more responsive to the gas pedal. Plus the fuel economy shot up big time. Before I was averaging 24.9 MPG when cruising on sport mode, and I would get an estimated range of ~520 mi after filling up and driving for a minute. It has gone up to a 34.1 MPG average when cruising, and my range hit 610 mi after I filled up.

2 questions:
Does it sound like they did an ECU reset?
What would cause such a dramatic improvement in performance?

 

You're thinking throttle body reset which is different. First let's consider that maybe you got a software update on your car which is why it's performing better. Second, the throttle body reset is very simple and can be done yourself. Do a search for it.