RobertSmalls' Prius C

[A.J.]

Congratulations on your purchase!
I was wondering which trim level did you get?

[RobertSmalls]

Upper grille block!



I cut a piece of black coroplast to the size and shape of the upper grille. I thought about making a template out of tissue paper, but it proved easy enough to cut it slightly large, do a test fit, and trim as needed.



I wonder how much of the lower grille I can block. I'd like to do a more sophisticated adjustable lower block than I had on the Insight. This would be especially helpful for this car, to reduce warm-up time.

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The car has 300 miles on it now, and I'm getting slightly better than the EPA Combined 50mpg. Weather is autumnal, and the driving has been a mix of highway, suburban, and urban.

Worst FE so far was about 25mpg on a 1.7mi trip to the hardware store today. The engine warms up awfully slowly in gentle city driving. It didn't help that I accidentally left the cabin heater on. This is a route I drive fairly often, so I'll keep working on it.

The engine bay is getting a bit grimy. This isn't necessarily a problem, but it is a symptom of aerodynamic issues:

1. There's an awful lot of radiator area. I'll keep an eye on engine coolant and inverter coolant temperatures, and I'll bet I can block most of the grille.

2. There's a hood gasket, but only between the headlights.

3. The underside of the engine bay is largely open. I'll see what I can do to correct that without drilling too many holes.

A view from the front:


The (total lack of) underbody panels:

Originally Posted by Cobb

Wow, Robertsmalls got a prius... Dont worry, it wont be long before you are approaching 100 mpg in that vehicle too.

I wish this were true. The C is good at many things, but getting 100mpg is not one of them.

AJ: I got the Two. I thought long and hard about getting the One, which would have been $1500 cheaper, but the One gets the fleet seats and is missing things like the center armrest, cargo area cover, cruise control, split rear seats, etc.

[Xringer]

The lack of cruise control kept me away from the C1. The C2 was the best choice for us.

What do you think of the headlights on low beam?

Please keep us posted on the amount of grill block used.
I might have to add one, if the MPGs start to drop when it gets real cold..

[Daox]

I vote for a full grill block. I was just at the Milwaukee Hybrid Group meet talking with Prius guru Wayne Mitchell (fire engineer on Priuschat) who knows a ridiculous amount about the different Prius' and HSD. The basic consensus of the discussion was for winter do a full grill block unless you are taking a prolonged highway trip, then just pull a tiny part out (we talked pipe foam since that is the most common block type). In summer you might need to open it up a little more, but I think he said he just runs all summer with one pipe foam piece removed. Warm up is critical for good mileage with a HSD vehicle. I have a 7 mile commute and most of my mods are focused on heating the car up and it has definitely helped.

[Xringer]

I just looked at the cars and found my Ford has a gap between the two heat exchangers.
(refrigerant & coolant coils)
That allows me to just drop a sheet of Coroplas between the two.
Just like dropping a sheet of paper into a file folder.
It's not real cold yet, so I'm starting off with a 30% block.
And will select coolant temp on the SG2.


'C' upper intake:
I noticed a small air-intake duct on the left (passenger) side.
Inside the engine compartment, it exits right in front of the air-intake for the ICE air filter.

It seems to me, the duct is designed to allow cold air to flow around the coils and directly into the ICE air input.
It's a bypass air channel. Should it be left open?

[RobertSmalls]

Xringer: I like the headlights. The car comes with DRLs, and lets the driver decide whether to run them or not. I actually use the second headlight setting (DRLs plus corner lights, headlights off) for city driving at night, when you need lights to be seen rather than to see.

Yes, that trumpet thing is the engine air intake. As you can see, it's not positioned to try to take in cold air. For fuel economy, you want your intake air temperature as high as the engine will tolerate. 120°F is a safe bet.

Daox, what time of year do you remove one piece of foam from your grille? How fast can you go / how hot can it be outside with a 100% block?

[Xringer]

I saw the little down-pointing 'trumpet' horn on the input to the resonator box-filter path, but what I was referring to, is the little air-duct that you can see on the extreme left end of the upper grill.
It's output is a few inches away from the trumpet horn intake.

I've seen these air inputs on other cars, feeding right into filter input.
I figured they wanted to drive cold air into the filter.

But, if we want warmer air going in, blocking that duct is a good idea.
Might keep a few insects out of the air filter too.

[Cobb]

The newer insight had that too. I tucked a water noodle in that gap and in the sumemr in stop n go traffic it makes the ac way colder.

Originally Posted by Xringer

I just looked at the cars and found my Ford has a gap between the two heat exchangers.

So the c is different than the base 3? I drove it like a rental car, got 49.9 mpg, drove it with some eco sense and got 65mpg.

[Daox]

Originally Posted by RobertSmalls

Daox, what time of year do you remove one piece of foam from your grille? How fast can you go / how hot can it be outside with a 100% block?

Just the other day it was 45F out and I was on country roads for probably 10 minutes. The full grill block was fine, no chance of the fan kicking in. I then got on the freeway (60 mph) and probably traveled another 10-15 minutes, and the coolant had gotten up to 204F before the fan kicked in and dropped the temps back down. I then turned the heat on medium and the coolant fan didn't have to turn on for the rest of the drive which was probably another 20 minutes or so.

[Xringer]

Originally Posted by Cobb

The newer insight had that too. I tucked a water noodle in that gap and in the sumemr in stop n go traffic it makes the ac way colder.



So the c is different than the base 3? I drove it like a rental car, got 49.9 mpg, drove it with some eco sense and got 65mpg.

Our C is a C2 model. Here's the model info.. The Toyota Prius c models and prices

The average C driver gets about 51 MPG Toyota Prius C MPG Reports | Fuelly