Who is BS'ing who?

fuel economy and speed are always going to be opposite each other THIS IS A FACT it can not be disputed it is physically IMPOSABLE to increase speed without a corresponding increase in energy (or fuel) any 6th grader should knows this, (barring any head wind, tail wind, up grade, or down grade)
now engine efficiency, gearing and other factors DO play a part in fuel economy, meaning there IS a speed range in which your car gets optimum MPG, or more specifically a point where the fuel usage vs speed graph levels out, meaning an increase in speed within this range only produces a small increase in fuel consumption, BUT there IS always an increase in fuel use in order to effect an increase in speed as long as you are traveling on a level surface with no wind,
when ever you get out of that peak efficiency range the amount of fuel needed to increase speed is much more pronounced, it does not matter if you are above or below that speed range, most cars are designed so that the optimum range is around 55MPH to 60MPH
the other HUGE factor with fuel economy vs speed is wind resistance, and wind resistance increases exponentially as speed increases, so you can see there is no way to DECREASE fuel consumption while at the same time INCREASING mph, in order to do that your car would need to put out MORE energy than it takes in, in effect creating a "perpetual motion machine" which any 6th grader will tell you is imposable, if you don't believe me ask one.
new old car truck bike train plane boat bus skateboard bicycle it doesn't matter the laws of physics apply to everything equally and at all time's everywhere for everyone no exceptions EVER! it is a simple fact and it can not be disputed period
if you have a problem with this remember Issac Newton and Albert Einstein were WAY smarter than you will ever be