55, 65?

 

definately 55, the higher you go from there the worse it gets

 

35

 

Actually, it can depend on the car, but most manufacturers tailor the car to make the best mpg at 55 in the highest gear. This is because the EPA standards are tested at 55mph.

So, 55mph is the quick answer. Typically, the rule is, the faster you go, the less mileage you will get. But, because gearing changes abruptly and engines are tuned for specific RPM ranges, this is not all true in practical circumstances.

 

Given any mph to choose from i would probably agree with jason at around 35-40 given the S2k's super low gearing...now with my torqueless civic i'd say like 50 or so would be optimal

 

In most cars, the best mpg comes in highest gear without lugging engine, so 45 mph is my guess.

 

For highway mileage the 2 biggest contributing factors are weight/rolling resistance and coefficient of drag, (Cd), which is directly related to front cross-sectional area. A very aerodynamic car with small cross-sectional area (s2000), will excel in both these areas. Therefore, the amount of additional hp needed to keep the car going at 55, 65, or 75 will be lower for the S2000 than that of a greater cross-sectional area vehicle which isn't very aerodynamic (eg. jeep).

 

I would assume the difference between 6000 cruising RPM and 6300 cruising RPM would be a huge difference, as the how cam is engaged (more power, but not much more RPM's, but at the same time, more fuel and more air). I think it would probably be around 55 for optimum MPG.

John

 

Actually Mike the S2000 has awful aerodynamics for it's size. I don't feel like looking up the CD right now, but it is not pretty. (Better than a jeep, but not by much )

 

During a road trip in my Prelude though Wyoming a couple of years ago, I got about 40 mpg at 55 mph. On the same trip at 80 mph we only got about 32 mpg.

My guess would be that the s2000 would fair about the same.