How to properly test modifications (AKA: don't believe every MPG claim you read)

[j-c-c]

I have made claims here in the past, where following all the parameters to do 'proper" testing just was not practical in trying to control all variables. My test, rather than do a sample to extrapolate, like a 200 mile round trip over the same section of roadway while controlling as many conditions as possible, I'd do a year's worth trips over all the same roads in nearly all conditions say for many tens of thousands of miles as a baseline for an average.
I'm satisfied with my results.