I haven't measured my consumption. Though if I had to guess, it would probably be about 3ml a day of 18mg
juice.
The 510 is apparently notorious for sopping up liquid at a really high rate (think of it as the ShamWow of the e-cigarette world), but it does give you that huge plume of vapor and better hit in return. So it seems a fair trade off.
Just a tip to keep from having to top off as often: When your draw starts to get weak (either flavor or hit), or you start to get that weird taste from your drags, tap the 510 battery side down against something (pant leg, cushioned arm of a chair, ect) several times, or hold it between two fingers and shake it till it looks like a butterfly. This will force more juice towards the atty, and keep you from wasting as much juice in the bottom of the cart.