Definite no go on the classic tags as actually using the truck for anything regularly would attract unwanted attention. Yeah, you can bet my high compression 460 would have a hard time passing smog as it was built for power and efficiency rather than emissions.
Higher compression is a big part of efficiency (of course we all know that here), but in a gas engine at least more compression means more NOx.
Lean mixtures also raise NOx, such as tuning cruise for best MPG and only allowing enrichment when actually required under heavier load.
More advanced ignition timing such as high advance at idle to reduce idle and off idle fuel consumption along with large unconventional amount of vacuum advance at light cruise will greatly increase overall MPG, but may put NOx over the government limit.
More advanced cam timing results in more torque down low enabling lower gearing for lower cruise RPM which yields greater MPG but also greater dynamic compression and thus more NOx.
So all these things that increase MPG are no good by the government, the EPA decrees MPG shall not be maximized... Or wait, CAFE is still around so they essentially outlaw the things that can be done to maximize MPG and simultaneously impose MPG requirements with an alleged goal of reducing fuel consumption. This is the same government program that eliminated 20+ MPG full size station wagons and replaced then with 10 MPG SUVs with less usable space.
Another notable achievement of the EPA is mandating ethanol blended fuels (primarily corn ethanol here) which cost more for less energy constant resulting in lower MPG. Not only do you pay more at the pump for an inferior product, but the money they steal from your income directly is used to heavily subsidize corn farmers and ethanol producers. If stolen money wasn't given to those along the chain of production and distribution it would not be an economically viable fuel. Other hidden taxes resultant from this policy are increased food cost as the artificial profitability of ethanol crops means less will be used for food and less land will be used to grow food. More hilarity ensues as corn ethanol is a net negative energy product, meaning it takes more BTUs to make it than it it contains as a finished product. Other types of ethanol I believe are more efficient to manufacture, such as sugar and switch grass.
I could go on about the stealing your money to give to rich people buying exorbitantly priced coal fueled cars, stealing your money to destroy thousands of perfect good cost effective vehicles and give it to rich folk buying new luxury cars while simultaneously tripling the price of reliable A to B cars... I'll stop there. Sorry, this stuff infuriates me.
