I'll describe my 2000 Honda Insight 5-speed and my results, then hopefully someone can project what it might do with aeromods similar to basjoos put on his Civic.
Since the Insight is .25 like the 2010 Prius, it's Cd is exactly halfway between basjoos before and after Civic Cd. In other words, the aeromods likely would yield about half the results of the 92 Civic.
The results are about the same as stock except my use of the FAS switch on the MIMA installation and occasional the hot air intake.
The 5-speed Insight at 70F+ on a level highway with no load or A/C will lean burn up to about 65mph.
Cruising at 45 on a highway, the results from cold to hot weather is 75-115mpg - 85-95 being more a more typical range.
MPG at various speeds:
- 110mpg @ 40
- 100mpg @ 50
- 80mpg @ 60
- 60-65mpg @65
- 50mpg @ 70
- 35-40mpg @ 85+
Since there is a speed limiter, it maxes out at 113mph (I did it twice over five years ago
)