We're hesitant to build any new features on top of EPA estimates for a number of reasons. We only have the
pre-2008 estimates for many cars because those are the only numbers that the EPA makes available in a data-import friendly format. They also only cover US cars, so the feature would only be available for those people who have a good EPA match on their vehicle.
We have the "EPA Estimates" section under the Log Book on vehicle pages where there's an EPA match. You could take a look at the +/- numbers under the estimate, the "Avg. Price/Gallon" amount in the "Cost Analysis" section and get a quick sense of how your price would be affected.
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