Eco Savings screen not working versus user error?

One of the alternative displays available shows $ saved versus your "other" vehicle with lower MPG. After one enters the lower MPG for the vehicle compared, and fuel price at fillups, a screen is available that graphs your fuel cost savings on a monthly basis. The months are labelled and the total miles driven by month is displayed under a bar showing $ savings for that month. The problem is once the savings reaches $200, the bar graph stops growing on the $ scale regardless of miles driven at the greater fuel economy. Am i doing something wrong?