Quote:
Originally Posted by Ken Fry
I think you'll find the two engines very close in BSFC at that HP.
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You could then convert from BSFC to % efficiency, and plug that number into this site's mileage calculator, remembering that only one line in the chart will be accurate, because for all other lines the BSFC will be different.
I played around a little to get a car that required about 22 hp at 70.
Calculator
This would be in between a 2004 Civic and 2004 Accord (which I use because I have the latter, so know its fuel efficiency). With average tires (.010), .35 Cd, 20 sq ft, 3200 lb, and .3 engine efficiency (which I guessed at right now, rather than actually looking at the Saturn chart) the MPG at 70 is 38.6. My accord will do 34. My accord is fairly immune to variation in cruise speed. I've cruised at 80 for long stints, even with a few hills, and it still gets 34 or close.
This points up a gotcha in the calculator chart, that being that as speed drops, engine efficiency drops too, so the figures at 80 (31.5) and 60 (47.9) are invalid: one too low, the other too high.
Your car will use significantly less than 22 hp at 70, of course.