Unfortunately for me I have shitty genetics when it comes to the abs. Even when my body fat is down around 10%, there is still a substantial cushion there. This is because I have the beergut genes in me, and it doesn't even take beer, most of the fat I have is stored on my belly. I keep pretty well to a diet that is high protein, and both moderately, but not extremely, low fat and low carb. I bicycle a lot, as it is my primary mode of transportation.
Admittedly, I have never really tried to focus specifically on the abs for any serious period of time, but I simply know that were I to do so, it would take more work than for most.