Who runs more?

I've finally finished the visualization for my grad school visualization class. We had to use data sets from the UCI Machine Learning Repository. I have choose the auto-mpg data set, which has data concerns city-cycle fuel consumption. This particular data set has 398 tuples with 9 attributes.

So I've decided to show which motor model (number of cylinders) runs more with one gallon.

The visualization is just bellow. I had computed the data using simple PHP scripts with PostgreSQL sql queries. With gnuplot, I plotted the output of the script, saving the plots as SVG files, which, using inkscape, I've made the proper manipulations to get this work.