I think your "tests" are good enough to give you a
basic idea that both bikes are about equal efficiency. While cyclometers are reasonably accurate, the "average" feature is a notoriously poor way to measure performance. There's also a bit of the New Bike Syndrome, where the new wheels will feel faster just 'cause it's a new bike. And I agree with Vik that you've got a big margin of error there.
A *slightly* more reliable test would be as follows:
- pick your testing route, preferably at least 20 miles of uninterrupted riding (e.g. a loop in a nearby park)
- use a stopwatch to track your times
- do at least 2 rides with each bike, preferably 3
- compare
Unfortunately, even with this method you're going to run into lots of environmental and effort variables -- temperature, wind, hydration levels, rest / recovery levels, training phase and so forth.
I.e., I have my doubts that you will get a more accurate test than what you've already done without resorting to a power meter.
That said, I would not be surprised at all that the BF Air is about the same level of performance as a high-quality road bike, particularly if you set up the position properly. If anything, riding position will probably have a bigger impact than tire size in terms of your effort & efficiency.
