This chart from the NYT was intended to show how the EPA has moved the bar on vehicle mileage ratings: 2008 estimates were lower than 2007 estimates across the board, regardless of manufacturer, model and city/highway.
The chart was built from one basic component, repeated for each model. I like the discreet gridlines (the white ticks) which enable readers to count off the mileage ratings.
The data is rich: ratings were given along three dimensions (model, year of estimate and city/highway). Readers can benefit from a stronger guidance in where to look for the most pertinent information. As the chart stands, it is merely a container for the data. It fails our self-sufficiency test: all the data were printed on the chart, and the bars add little.
In the junkart version, I use knowledge of the data to structure the chart. First, noting that sedans, hybrids and trucks/SUVs/minvans have different levels of mileage ratings, I clustered the models into three groups. Secondly, the city and highway ratings were separated into two columns as I consider the between-model comparisons more important than city-highway comparisons. The chart is a dot plot, with a vertical tick for 2007 estimates and a dot for 2008 estimates. It's easy to see that all dots sit to the left of vertical ticks.
More subtly, we can also see that the hybrids appeared to have been penalized more. Or perhaps, the higher the rating, the larger the downward adjustment...
Source: "Mileage Ratings Are Still Estimates, Though Closer to Reality", New York Times, Sept 16 2007.