Gas
Let’s start with the most noticeable piece of the puzzle. It’s pretty simple: The faster you go, the more fuel your engine burns. Plus, air resistance makes a big difference at highway speeds — all adding up to more frequent trips to the pump.
“But my car has a great MPG rating,” you might say. That rating is actually an estimated average. Even if you drive the most tree-hugging hybrid on the market, going easy on the gas will make every gallon go further.
It might not feel like it matters much in the moment, but over weeks and months, having a heavy foot adds up in a very real way.