Granted, the reasoning is fairly dubious, comparing the two emissions side by side would obviously render the reasoning that higher speeds create fewer greenhou

Granted, the reasoning is fairly dubious, comparing the two emissions side by side would obviously render the reasoning that higher speeds create fewer greenhouse gases false. But having said that, the opposite isn't actually that "green" either, reducing every vehicle despite its optimal torque range to certain speed limits isn't an instant reduction to carbon production since you will generate more of it by running a lower powered engine at higher rpm's than it was designed to run optimally. So you can't make an absolute statement in either way actually. You can only adjust to the vehicle base in use currently if you want to optimize efficiency, speed, fuel consumption and emissions.