That can’t be right, it would leave your cars immobile after like 6 years, and getting half the range out of a tank after 3 years.

Cars are good for 20 years still going roughly as far on a tank as they did. I’ll believe 10% loss of mpg over a lifetime, I don’t track that closely, but 10-20% range loss on a tank per year, nahhh.

Sorry I meant a 5mpg decrease overall not every year. That would fit with the 10% you describe.

That is not normal. Every car I have owned has maintained its gas mileage unless something was wrong with it. My current vehicle is over 20 years old and is actually getting better gas mileage than it was when I bought it 3 years ago. I do keep up on maintenance more than the average person does tho.

Honestly in my experience, small displacement cars have typically gotten OVER epa estimate mpg. I had a 25 year old acura that got 35mpg easily each tank, epa estimate when it was new was like 30mpg iirc.

I'm driving a 2013 F-150; it's got ~20mpg since I got it in 2014. The 2004 Corvette still gets approx. 30 (mostly highway), although it desperately needs new fuel injectors.