[JRMichler]

Here's an outline of what I'd like to say in a similar situation:

Get their attention: "There are ways to drive to work in the same time while using less fuel."

That leads into timing traffic lights, different routes, DWL, and mild coasting at exits and stop signs. Also timing stop signs: "If there's six cars backed up at a stop sign, back off the gas and try to arrive as the last car is leaving. Burn less gas and get to the stop sign at the same time".

The close by something like: "I have discussed techniques that decrease your fuel costs without changing the time it takes to drive. There are also more advanced techniques that save more fuel at the expense of time. Those are a topic for another time".

Keep in mind that your target audience generally believes that the only way to save gas is "drive like a grandma", annoy everybody else on the road, and take forever to get there.