Modifying a vehicle to be something it wasn't intended for, isn't so terrible.
It's what I and many others on this site are doing all the time - we just go in the other direction.
None of the cars I've owned while posting on this site have been economical by design. If I didn't enjoy the challenge, I'd by a used VEi civic - it's highway rating is better than I've
ever gotten from the Astina.