[iplaysdrums]

I drive a 2004 MINI Cooper S which I've begun aeromodding, and I've noticed something that seems counterintuitive: particularly when going uphill, my KiwiMPG instantaneous MPG readout gets higher as the RPMs climb, to about 4,000, at which point it begins to drop off again. I've hypothesized one of two things to be true:

a) My KiwiMPG doesn't know what the heck it's talking about, because I can't possibly be getting 37mpg under load uphill in 2nd gear at 3,500rpm.

or

b) As the supercharger kicks in, the air forced into the engine actually leans out the air/fuel mixture when I'm not mashing the throttle.

If a) is true, then I'll just have to live with it until I can convince myself to buy a ScanGauge. If b) is true, then it logically follows that if I were to induce higher boost at lower RPMs, if I'm able to tame the impulse to bury the needle, my economy should improve pretty dramatically.

Of course, it's entirely possible neither is true, and it's something I never would have thought of that's happening. I may just be looking for a reason to buy a 19% smaller supercharger pulley, thereby making the car faster, in my ever-self-defeating internal conflict of speed vs. economy.