Mg1 & mg2 temperature???

Ok, you asked:

	Column 1
0	[th]Blocking[th]MPG[th]+ MPG[tr][td]none[td]51.6[td]0+ MPG[tr][td]recessed[td]53.3[td]1.7+ MPG[tr][td]conformal[td]53.6[td]2.0+ MPG

Source: Why mileage gets worse in winter | Page 5 | PriusChat

A recessed, total block gives 1.7/2.0 = 85% of the maximum, conformal block, or ~0.3 MPG. Located behind the horizontal grill, it would be invisible to the outside world, and protected. However, there are technical challenges to achieving an air-tight seal behind the grill.

A better approach would be to build a pair of foam-and-fiber glass, air-inlet, inserts with one or two movable parts. They would have an aerodynamic profile and relatively smaller, open inlet whose fully open area is the same as the area between the existing horizontal vanes. The reverse side would be designed to smoothly, slow the air down to increase pressure and reduce radiator cooling drag. Most of the blocked air would simply flow over (preferred path), under, or a small part, to the sides. But there is a mechanically simpler but more advanced design that does not require a moving part other than the vehicle itself.

Regardless of the air-insert design, the inserts are as exposed to the same road impact and damage as the bumper cover. A better design is cheap (i.e., easily replaced or repaired,) flexible yet impervious to air and water and sunlight resistant cover. One optimum solution would be air inflated, rubber tubing . . . think a customized, inner tube . . . or rubberized fabric perhaps filled with foam-rubber. Expanded, pool-noodle foam would be another option and easily formed using hand tools.

Bob Wilson

 

I measured MG1/2 temps peaking at 120F in my typical pulse and glide city commuting. 90F inverter coolant temp. 10 miles each way, ambient 68F, 60MPG indicated, no grill blocking, except for lower grill stone protection mesh 30-50% blocking at the best. I also used Torque Android app.

 

Good ideas for the do it yourselfer, but I was thinking of something more stone ax simple from the factory that would work for Joe don't give an S consumer. It might take some minor cooling system re-arangement, but 1950s Volvos had something that resembled a heavy duty roller window shade in front of the radiator with a cable with a handle under the dashboard that you pulled to operate it. With modern control systems it would be easy to automate something like that to the point of being highly idiot resistant and have the shade position controlled by coolant, inverter, MG and whatever other temperature was important.

 

A few of the new Eco Trimmed cars like the Chevy Cobalt and Ford Focus has this.

From the 2013 Dodge Ram truck

 

The Ford solution wouldn't bother me here in the non-snow part of Northern California, but it would make me nervous in snow and sleet country.

How does the Dodge system work? It is at least a little protected.