hyperme

I've never had problems and I've always topped off.

bigL

iTrader: (3)

I've heard alot of people say that. I've also worked in a Lexus service department and sold people costly charcoal canisters that couldn't believe topping off could cause this. Search it. Like I said I'm not sure about the HS but that is the case on other models and manufacturers.

JamesDemo

I have always topped off because I hate getting gas. Usually on the first auto shut off I always get another $2.00 bucks + in. I get gas at the local costco and now the pumps have a warning window with a sound to bring your attention to: which reads- DON'T TOP OFF! and makes a buzz sound and the more you top off the louder it gets
I have never read about a filter but nothing would surprise me? If any one has info on the filter please post. It would be a bummer for the topper’s

hyperme

I get more than 2 gallons in after the first click. I can't see stopping there. That buzzing sound would send me to a different gas station if it's that annoying.

Jherb350

iTrader: (1)

My SC400 had the overflow charcoal filter. After I had topped it off on a couple of fills I started to notice a gasoline smell when I would get out of the car. At first I thought it was a gas leak, but couldn't find one. After some research I found out it was the charcoal filter. I stopped topping off after that and the smell eventually went away.

Not sure if Lexus still uses the charcoal filter but if you start to smell gas I would stop topping off for a couple of fill ups.

Oh and that filter isn't cheap either.

Hyper, congrats on the great mileage keep up the good work. I wish my wife could get half those numbers out of our GS450h.

Magellan55

Some info on why not to top off the tank. Basically that extra 2 gallons you're getting beyond 14.5 is the designed "vapor headspace" needed for the tank and vapor control systems to work properly. You say you haven't had a problem, but you've only owned the car for 2000 miles. The damage you're doing, not to mention the environmental problems you may be causing (what's the point of hypermiling if you don't care about the environment?), is longer term and as others have posted, require costly repairs way in excess of any savings you're getting from hypermiling.

http://www.epa.gov/donttopoff/

Thread on this on the similar Prius setup: http://priuschat.com/forums/gen-ii-p...-believer.html

Some discussion on gas tank design:
http://www.stanag.org/pdf/fuel-gas-tank-accuracy.pdf