Tip o’ the Day: Go Topless
It's really just a bad habit, isn't it? Trying to fill your gas tank so that it holds every possible drop is something that most people have been doing since they bought their first car. But why is it so important to us? In the "old days" when we used to pay cash for gas, we were trying to round it off to a nice even number. That excuse doesn't hold up anymore.
Do you notice that you tend to follow rules better if you know the reason why it is a rule? Today's car-related tip is hopefully going to set us all straight on that why, so that we'll finally follow the instructions at the gas station. After this, when you read the "DO NOT TOP OFF" notice on the gas pump, that's exactly what you'll do.
First of all, gasoline vapors are harmful to breathe. They help create "bad ozone days" and release toxic pollutants into the air. In fact, gas pumps have built in vapor recovery systems that feed the vapors back into their tanks, instead of releasing them in the air. When you top off your tank, you could damage that station's system.
Topping off can also cause spillage. That gasoline on the asphalt is going to go somewhere, and most likely it's headed to your local creeks and rivers. Plus, a shot glass full of spilled gas produces the same amount of emissions as driving a car 56 miles.
Hopefully these are enough reasons to stop topping off, but visit the EPA's Don't Top Off site and see Santa Barbara County's Don't Top Off (pdf) for even more reasons.
Rebecca says: I've been trying to convince people for ages to stop topping off, but I didn't have the facts to explain why it was important. This tip is getting forwarded on today - I've got a point to prove!
Got a tip you'd like to share with Rebecca? Leave it in the Forum.
Tags: filling, fuel, gas, station, top+off
February 22nd, 2007 at 5:38 pm
I'm a green type of guy but I just don't buy either of these arguments.
When you top off your tank, you could damage that station's system.
The engineers who designed the vapor recovery system didn't consider that sometimes liquid gasoline would be taken into the hose by drivers who weren't paying attention or a defective nozzle that doesn't shut off? I have no experience with such systems but I'm very confident they're designed to handle this obvious situation.
Topping off can also cause spillage. That gasoline on the asphalt is going to go somewhere, and most likely it's headed to your local creeks and rivers.
Not where I live. In a California fueling facility spilled gasoline or diesel must flow into a sump for separation to prevent exactly that possibility. I suspect most states have similar laws, I've bought gas a lot of places and all modern service stations seem to have huge concrete pads with sophisticated drainage systems.
I'm not saying we should go back to topping off our tanks, but surely there are better arguments than these.
February 22nd, 2007 at 6:11 pm
Rebecca -
Gas pump nozzles shut off when they detect air pressure rising rapidly, as when the gasoline starts to rise in the tank's filler neck. Unfortunately, the pressure sensors are rather old tech and vary considerably from pump to pump. I "top-off" not to get to the nearest dollar, but to make sure my tank is truly full. I have had instances in many stations where the nozzles shut off when the tank is only half full! This seems to occur most on vehicles with long filler necks, or on my Prius that has a rubber seal around the nozzle hole - causing air pressure to build quickly. I like to make sure the tank is full to the top so I can keep accurate MPG numbers tank-to-tank, and especially when I travel long distances. If you don't top off, you have no accurate way of knowing exactly how full your tank is (yes, I am an engineer, I admit it!)
As far as spillage, it is my understanding that the "Do not Top Off" warnings on the pump handle are in place on systems that have vapor recovery such as in California smog areas. They are afraid any liquid fuel getting into the system will temporarily overwhelm it. I don't believe it is in any way related to spillage onto the car or ground.
Frankly, I would like to see the fuel stations and vehicle manufacturers standardize a new, high tech delivery system that has a more positive spillproof hose-to-car connection, vapor recovery, shut-off feedback from the car to the pump, etc. OK, well, really what I would like is instant-charge electric fill stations, but reliable technology isn't there for that yet!
February 23rd, 2007 at 3:08 am
Michael, I’m going to check the next time I fill up, but I’m pretty sure my local gas stations are just asphalt. As for damaging the station’s system - it seems strange, but I did find that fact quoted in several reliable sources.
EndTheAddiction, I’d like the instant electric charge stations, too!
I’d love to hear more points of view on this issue. I do, however, believe the EPA, and I still believe that topping off is an obsession we can do without.
What do you guys think of the part on the EPA website that says: “Topping off the gas tank can result in your paying for gasoline that is fed back into the station’s tanks because your gas tank is full.”?
February 23rd, 2007 at 10:25 am
Here is another reason and probably the one that would concern most non-eco conscious people. Most pump systems are designed so that after the first time it automatically shuts off, anything pumped after that goes into the pump's reserve in the in the gas line. I worked at a Shell for years and this was the case with our pumps. I would tell people all the time they are simply wasting their money, nevertheless they topped-off everytime.