Don't feel like reading the details? See bolded sentence below, otherwise... ------------ Hello all, I've read through pages and pages of grill blocking info, and found it convincing enough to try it out on my recently purchased 2007. I half blocked the top grill and 3/5 blocked the bottom grill tonight (15-20F temps) for the first time, and managed 57.5 and 62.1 mpg from the display over about 25 miles each way, half hilly quasi-highway (40-50mph), and the rest pulse-and-glide land...so thank you all for the suggestions, I doubt I could do that otherwise in temps this freezing. Undoubtedly somewhere in the thousands of paragraphs this is answered, but I wasn't able to find it (maybe since I don't have the technical background to understand certain parts of the discussion...) - is the radiator which some suggest to NOT block found behind the top or bottom grills? I've read some posts saying to entirely block the top, other to entirely block the bottom. Since I don't have a Scangauge, I am only using this in pretty cold temperatures to be safe.
Hi Mike: With those temps. you can block fully the upper and the bottom as well. Some members leave a portion open on the lower grill , drivers side. I block it all! Remember if the temps. get high a light will come on.If this happens just remove a couple tubes. You should be OK up to 50 d. and then you could remove about half the bottom. Hal
Hi Mike, Below 90 F, you can block all of the top grill in a 2nd Gen Prius. I would not recommend blocking all the bottom ever. My commute driving is similar to yours, except maybe not as hilly. At 32 F I would block the passenger side 1/2 of the lower grill in my Gen II Prius. When wether is below 15 F , I would then block another 1/4 of the lower grill (leaving 1/4 open on the far drivers side). The reason for this is the transmission is air cooled, by the air that flows into the engine compartment from the lower grill area. Additionally, the inverter radiator is in this area on the Gen II. This is different in the Gen III, which has the inverter radiator behind the upper grill. Consequently, on the Gen III one does not want to block the upper grill. This may be the source of your confusion.
