vertrkr said:
The Ridgeline would never get that milage because of it's poor aerodynamics. The reason Honda didn't put the iVTEC VCM engine in the Ridgeline was they found it would rarely be able to use the 3 cyclinder mode because it's just pushing to much air.
A 5,000 pound GMC Silverado 4X4 extended cab gets 15/19 MPG (per the EPA) with the 310 HP/335 LB-FT 5300 VORTEC HO.
A 5,000 pound Grand Cherokee gets 14/21 MPG (per the EPA) with the 330 HP/375 LB-FT Hemi.
But a Ridgeline, which is 500 pounds
lighter than either one, couldn't at least equal the current Ridgeline's fuel economy if it used a similar V8 engine?
What about the Honda S2000? Are bad aerodynamics the issue there, too? That only gets 20 city/26 highway MPG (per the EPA) and makes a mere 240 HP and 162 LB-FT from its "efficient" 2.2 liter 4 cylinder. The 400 HP/400 LB-FT 6.0 liter V8 Corvette, which is 350 pounds HEAVIER, gets 19/28.

And that 'Vette will blow the S2000 into the weeds without even trying.
The same holds true for the Acura NSX. That never got decent fuel economy, relative to its aerodynamics, weight and power output.
High revving, small displacement engines with relatively high specific outputs (HP/liter) simply aren't all that "efficient," despite the hype that people like to throw around. That's because they have to geared very LOW in order to go. And that kind of gearing equates to lots of revs, which are the exponential enemy of fuel efficiency.
I challenge you to name a single Honda or Toyota automobile that can equal or beat the "inefficient" Corvette's 6.0 liter V8 on a HP/Engine weight and HP/MPG basis.
C6 6 speed 'Vette:
400 HP/485 pounds engine weight = .825 HP/Pound
400 HP/ ((19 + 28)/2) = 17.02 HP/MPG