And even with the old, Geo motor they have already exceeded 80mpg. The new engine will just be icing on the cake.
I don't think so. The new motor is close though.
As Ty correctly points out the old Geo Motors has not actually exceeded 80 MPG. Instead EM has told us that their simulations show that the final vehicle configuration with the IAV engine should be able to achieve a little over 81 MPG on the EPA test. While this is all done virtually these MPG simulations are very well understood and very accurate to the point that they are in common use by auto and motorcycle manufacturers all over the world. The Elio vehicle computer model should be quite good at this point as EM has gone through several generations of prototype vehicle builds so they should have accurate numbers for the vehicle design and the IAV engine may be untested however it is actually designed to be detuned for MPG which leaves IAV some margin to work with so even if they fall a bit short in the overall design they will very likely still be within the window that EM needs.