Quick proviso: Of my two cars, I drive one for mileage, one for fun. This post concerns the fun car
Last summer, I took a long road trip through the southwestern states. At no point was I driving for FE, but there were some portions where topography and traffic conditions lent themselves to fuel efficiency. During these situations, I averaged around 33 mpg.
I drove extremely quickly through Death Valley, enjoying every drop of performance the car had to offer. Filling up in Pahrump, Nevada, I logged my best tank of the trip: 34.7 mpg.
Could Death Valley's below-sea-level (-200 feet) elevation have anything to do with this FE result? I usually average in the 26-to-28 range during spirited driving mixed with highway. It seems incredible that I could run for extended periods at high RPM and still achieve nearly 35 mpg.
For reference, I was driving a 2006 Mazda MX-5 Miata 6MT.
TIA for your thoughts!