The table: (addit: made it clearer to see the 1/2 efficiency jumps)
1L/100km = 227.12mpg

2L/100km = 113.56mpg
3L/100km = 75.63mpg

4L/100km = 56.74mpg
5L/100km = 45.42mpg
6L/100km = 37.85mpg
7L/100km = 32.45mpg

8L/100km = 28.39mpg
9L/100km = 25.24mpg
10L/100km = 22.71mpg
11L/100km = 20.65mpg
12L/100km = 18.93mpg
13L/100km = 17.47mpg
14L/100km = 16.22mpg
15L/100km = 15.14mpg

16L/100km = 14.20mpg

I started out just wanting the conversion, but what I got from it:

To go from 75 mpg (3L/100km's) to double that consumption only takes 3 more liters.
- but, to double that consumption again, I need 6 more liters. (duh)
-- yet, it is taking more and more fuel to worsen my efficiency by the same percentage. So I feel ok with the fact that I'm on the gas a little more than normal, because, well, I would be on the gas anyways, and a little less efficiency uses a little less fuel than the last enjoyment increment.

Now, in the other direction:
227 mpg looks real nice, but I won't get that except at idle on a dead straight road, maybe.
- so that's why I don't see those smart cars at 82 mpg, because even in those cars, you have to be on the gas a minimum amount. So I'm glad I kept to the larger FITmobile.