Your link doesn't seem to work, but I can tell you that the way 90% of the population drives these "40mpg" cars, they will never see that magic number. When they do 80+ on the highway, they may as well be driving a solstice, because they aren't getting better than low 30s!
I recently bought a hyundai veloster as a daily driver. It's comfy, practical and corners very nice. It is not fast by any stretch, and I drive it like a slow car. I have yet to break into 40s (best 38.7 actual mpg), while I routinely get high 20s-low 30s on my GXP. The EPA estimates have gotten a little more conservative over the decades, but they are still rather optimistic IMO.
2008 BRAZEN GXP - 5M Loaded Tuned to 22 PSI with HPT, AEM water/methanol injection kit - 4gph, Hahn Racecraft Intercooler. Solo street race exhaust, Catless, LE5 Throttle body, ZFR 6758, custom CAI 307whp on dyno dynamics - stock turbo (21 psi) 463whp/454wtq EFR 6758 26-27 psi,100 octane - tuned by me
2006 SLY 2.4 Comfort and Power - TRADED 28-Aug-2008