Well, they're not fudging the numbers, the EPA is with their outdated tests. The Carmakers themselves have no input on those numbers. EPA mileage tests suck in general and are really bad when it comes to determining mileage from anything other than piston engines, like hybrids or rotaries.
25MPG is virtually impossible in the RX-8. The absolute highest reported on RX8Club is 23mpg, and 12-15mpg is the average for mixed driving. Most people would be happy to just get 18mpg on long highway trips, let alone in the city as the EPA claims. 10-12MPG is not uncommon at all.
And all that is after about a dozen updates to the ECU that Mazda has released that have improved mileage. Single-digit mileage was pretty normal when the RX-8 first came out, even though the EPA sticker still said 18/25.
