It might not accelerate as quickly as it once did; the engine may not run as smoothly as you remember, or the fuel economy ...

Fuel injectors can get gummed up with dirt and fuel residue over time. Photo credit: David Traver Adolphus / Autoguide.com.

“The cleaner the fuel, the more efficient it will burn ... now even the smallest amount of water can cause an injector tip to blow and the engine to need overhauling, says Dan Bigelow ...