You can still modify your order if you do not have the build date yet. But for some people, like me, it will always be "what if"? I have Standard range RWD and when I was on a trip from SF to LA, I was thinking why didn't I order Extended range. Then I came back home and was like - good thing I didn't order Extended range - I don't need it for my daily commute . Always "what if"...I most likely would have been fine ordering a standard range then.
Frankly, these tests are meaningless, because everybody's driving conditions are different and the efficiency can vary widely. Just recently I've driven from San Francisco and got the efficiency of 1.8 mi/kWh. Not because of the temperature, or wind, or speed, but because of slight elevation. Then going on I-280 the efficiency went to 2.7mi/kWh, that's a 50% improvement in a matter of 20 minutes.