Originally Posted by kickstand
So the weight is more of a problem for fuel economy than the emissions regulations? Throws my comment right out the window.
Yet, they're a function of each other - so you're not totally out of the scope of the problem. How much do you think this exhaust weighs?
Not only do you have the SCR for NOx, it needs a tank and injection system for urea, the DOC, DPF, additional injection system for regen, many extra sensors AND some of that exhaust pipe is double wall for retaining heat.
Everything plays a part - I just want the misconception out there that the emissions system increases backpressure so much that it cost you 5 mpg.