Do nitrogen-filled tires deliver better fuel economy?

IF it’s true that N2-filled tires lose pressure more slowly – AND if you’re a slacker when it comes to checking pressure – then yes, your tires will deliver better fuel economy on nitrogen, simply by virtue of being inflated correctly more of the time.  But there is nothing about the chemical properties of nitrogen that cause it to imbue a tire with lower rolling resistance than air.  A tire filled with nitrogen to X psi will deliver the same fuel economy as a tire filled with air to X psi.  If it actually did make a difference, car manufacturers – always desperate for even minor increases in fuel economy – would specify it in the owner’s manual.