I have a 2007 TCH and does it make sense to block the interior of the grill with a cardboard wind block so that cold air does not reach the radiator and alllow the radiator to stay warmer in the winter time?

The goal is to reduce the chill of the wind which forces the gas engine to work less and the electric more. If the engine fluids cool because of the cold draft, the gas engine has to engage when i drive.

Any thoughts or other ideas on this subject?

 

Yes, absolutely you can, and probably get some very noticeable benefits. Even better would be a "bra" which totally blocks most of the grill, because you'd also gain some aerodynamic benefit. Manufacturers don't address these issues in cars because they don't do fuel efficiency ratings in cold environments, and only a fraction of their end users have use for these modifications, and even those are seasonal.

You may have noticed some large trucks in the winter with their grills tarped over completely, and then maybe a corner folded to allow just a little air flow. That'd be the idea. A piece of cardboard like you describe works great too, and making it cover 3/4 of the radiator is just fine. Just don't forget it there when temps get very much above freezing.

 

you can. mof, my wife's driving her RX300 with half radiator covered by cardboard right now.
just keep in mind, you have it crossed. gas engine works more and electrical motors less, if it's colder outside.
The goal is to reduce the chill of the wind which forces the gas engine to work less and the electric more. and this is reducing mpg.
also, you can extend your ingenuity and cover engine with a thermal blanket. so that it warms up and stays warm better. as far as you have it secured away from moving parts on the pass side of it.
but there will be much to cover, as gas engine kicks in mostly to keep HSD and cat at operating temperature. now, those are fully exposed from the bottom and sides to ambient temperature. good luck insulating all that.

 

hmmmm... engine bay belly pan sounds like a good idea... both for aerodynamics and temp preservation reasons

 

bump.

had charcoal, from dealer, filter installed yesterday. $30 plus.
Drove this morning - not a smell. hour drive, heavy rain, that's when smells really stay low and get into vents.