For 2013, Volkswagen is introducing a convertible version of the Beetle, and the EPA estimates are out on the vehicle, showing that the convertible will get the same mileage as its non-convertible sibling.
Despite the added weight gained because of the convertible setup, the drop-top Beetle retains the fuel numbers of the regular car, in all three forms. The Beetle TDI convertible, when equipped with a manual transmission will get an estimated 28/41 mpg city/highway. For the turbo version, the car will likely get 21/30 mpg. The I-5 gasoline engine has yet to be rated, but if it keeps with the trend of being the same as the existing Beetle, it will net 22/31.
The DSG-equipped convertible models have not been rated yet either, but just for reference, the non-convertible variant of the Beetle equipped with DSG will get you 22/29 mpg for the 2.5-liter five, 22/30 for the Turbo, and 29/39 for the TDI.
[Source: Car and Driver]