I got a response from Karma itself saying there are some differences between the Fisker and the Revero, although it is possible to upgrade to an earlier version. Here is the original message:
While the 2012 and Revero may look a lot alike, there are significant changes under the skin.
The Revero can do things like accelerate more quickly and charge at DC Combo charging stations, but these are not changes that result from new software alone.
This is the case for the infotainment system as well. The wiring harness, sensor package and many other systems which integrate with the screen are specific to the Revero – so you couldn’t simply remove the 2012 screen and plug in a Revero’s to make an upgrade.
With that said, we have developed upgraded software packages for the 2012 vehicles and they are available for free at any authorized Karma service center.
Unfortunately, the nearest location to Spain is the Emil Frey service center in Switzerland. We realize this isn’t a convenient location but if you’d like to get in touch with them, we’ve included a link to their contact information below: