There does seem to be an argument against topping off that is more financial than immediately environmental: overfilling can clobber a car's emissions system. See, eg, http://ask.cars.com/2007/07/gas-top-off.html

Of course, since emissions systems are about breathable air, this argument, too, is environmental.

At least now I shouldn't have to ask the attendant not to top it off quite so often.

Believe it or not,(mild blush) some of the general public is unaware of the (now obvious) reasons why it matters. Now the familiar "top-it-up?" will be met with a citizen's arrest, bookem JackBo.

Hopefully, since the stations are in the game to sell as much gas as possible, my "false clicks" won't stop the attendant from actually filling my tank. When I'm in self-serve states, I've pumped as much as another full gallon of gas into the tank.

How much money/time/taxes does anyone want to guess that will be spent "educating" gas stations and attendants?

I went through California and Nevada in a rental car last week. It was my first real road trip in quite some time.

After nearly running out of gas between Shasta and Susanville (because I didn't believe there could really be that many miles between gas stations) it was totally awesome to overfill the tank when I finally found some fuel.

Since I live in Oregon, I am happy to let the station attendant worry about complying with this law when it goes into effect. I assume (but I shouldn't) that there is some legitimate reason that the legislature passed it.

Report: 98 Percent Of U.S. Commuters Favor Public Transportation For Others, The Onion, November 29, 2000 | Issue 36•43

WASHINGTON, DC–A study released Monday by the American Public Transportation Association reveals that 98 percent of Americans support the use of mass transit by others.

Traffic moves slowly near Seatte, WA, where
a majority of drivers say they support
other people using mass transit.

"With traffic congestion, pollution, and oil shortages all getting worse, now is the time to shift to affordable, efficient public transportation," APTA director Howard Collier said. "Fortunately, as this report shows, Americans have finally recognized the need for everyone else to do exactly that."

Of the study's 5,200 participants, 44 percent cited faster commutes as the primary reason to expand public transportation, followed closely by shorter lines at the gas station. Environmental and energy concerns ranked a distant third and ...

The above photo dates to the mid-'90's at most.

Modern pumps have a return line that routes excess fuel back into the station's tank. Overfilling is a big money maker for gas stations.

Waste of time. Here come the environmental cops, enforcing evreything green...next, it will be illegal to fart, thereby releasing methane into the atmosphere.

Gimme a break!!!!

I think the people complaining are the ones with too much time on their hands. In Oregon we don't pump the gas, so the change in behavior required from us is exactly zero. You won't pay a dime more (and will avoid paying for gas not put into your tank) and you will not have to breath so much bad juju. It's an admittedly small step, but what's the argument for NOT harvesting all the low-hanging, easy air quality measures?

Filling Up? New Law Bans Topping Off

The next time you “fill up,” your service station attendant won’t be topping your tank off. Oregon’s ban on topping off the tank at the pump takes effect July 1. Why the law? Topping off during fueling can cause gasoline to spill and release benzene and other toxic pollutants into the air. That’s unhealthy for both drivers and station attendants.

There are many myths around the practice of topping off. You might think you’re getting more gas in your tank by filling past the “click” but in fact this is rarely the case. One of three things actually happens:

*The extra gas fills your tank's vapor control system, clogging it and rendering it inoperable. Gas in the vapor control chamber evaporates eventually.

*The extra gas is actually captured and pumped back into the gas station's underground holding tank. In this case, you're paying for gas you don't receive!

*The gas simply overflows and spills on the ground or down the side of your vehicle. That's not a good thing for anyone.

Learn more about Oregon's No Topping Off law by visiting DEQ's Gasoline Vapor Recovery Program web page.

http://www.deq.state.or.us/aq/permit/vapor/vapor.htm