Well, when you are idling, you ARE getting no speed! Thus no MPH!
Yep, just a typo there.
I think the best thing to do on the "idling" bit on the pledge card may be just to remove the examples.
If people turn off the engine when idling more than briefly, it is their opinion of what breifly is. For some people, it may mean while at a traffic light. For other people, it may mean having the car run while parked in the driveway, to run inside the house and get something you forgot.
If the examples are eliminated, wouldn't it leave "briefly" up to the mind of the driver?
We would still be saving fuel no matter what "briefly" is defined as.