Insulating grill of Prius

It has been recommended that I insulate the grill of my Prius, in the winter ( removed in summer) to increase the gas mileage to 50 mpg. The effect is to allow the engine to run warmer. My question is, in the long run, will this harm other components as well as the batteries (located under the seat)?

I would never do that. Toyota has a good idea on how to manage heat in the engine, and if you mess up, you toast your engine. Not worth it.

I don’t recommend it. If it was a good idea, Toyota would already be doing it.

The fuel economy of your Prius declines in cold weather because cold air in the intake increases the amount of gasoline needed in the air/fuel mixture, and because you are running the heater. Insulating the grill doesn’t solve either of these problems.

The other issue I have with the idea is that this might increase the amount of time necessary for the electric fan to run, which would decrease fuel economy.

The best way to improve your winter mpg with a hybrid is to dress warm, thermal underwear and heavy parka, and don’t turn on the heater. If you leave the heater controls “off” then the gas motor won’t fire up until the batteries call for a charge. Once your gas motor is running to charge the batteries then you can turn on some heat, but keep the temp as low as possible. All this may not be practical, but hybrids aren’t nearly as efficent in winter because the gas motor runs more just to provide cabin heat.

Covering the radiator won’t make any difference, there is a thermostat in the motor to have the gas motor run at the most fuel efficent temperature.

I’m not 100% sure, but my impression is that the first time you exceed creep speed the engine turns on and runs until it reaches operating temperature and then will cycle the engine to maintain it. Just as with any car, the Prius’s gas engine runs much less efficiently cold, so the computer keeps it warm. So unless you’re driving a very short distance and not exceeding creep speed, having the heater on shouldn’t matter.

I agree with the others that blocking the radiator is not something that should be done on a Prius (or IMHO any car). If your car has a functioning thermostat, the effect of cutting off the airflow should be negligible and increases the chance of overheating at highway speeds, even in the winter.

In a diesel this helps the engine warm up quicker. In a gas engine in areas that are not in the Arctic Circle it makes little difference. And could theoretically make it run too hot making the electric cooling fan come on which will use more electricity and in a vicious cycle, drain the battery more and necessitate the gas engine coming on more frequently to charge the battery.

Say it with me kids : “There’s more to life than getting good gas mileage”