Why mileage gets worse in winter

Ethanol was turned into snake oil.

Most people are unaware of the effort long ago, before the boom.

It was a long-term project to find fuel from waste and fuel from local providers. It was efficient, renewable, and green, none of the proganda we deal with now.

 

Anyone tried this?

 

pretty much the same thing as water wetter, slightly increases the heat transfer/

 

Wouldn't it make the radiator transfer heat faster? All metal surfaces in contact with coolant would, can't see it helping heater efficiency. I'd save the $10 and buy 3 gals of gas with it.

 

I agree, you can heat the car for a long time on 3 gallons of gas.

 

Seems unlikely that the thermal transfer could be improved much. One could decrease the warm-up time by reducing the specific heat of the radiator fluid. However, the specific heat of the radiator fluid is what allows it to do its job. Imagine if you will, replacing ALL the fluid in the radiator with air. It would definitely 'decrease warm-up time', at the cost of not preventing 'overheating', 'seizing', and 'brickifying'.

 

If you remember to change to a low specific heat fluid in the winter and a high specific heat fluid in the summer it may be beneficial. If the winter fluid was about half the summer's specific heat it may work, but then it would also take half the time to cool down, in a Prius you don't want it cooling down faster either in winter as the engine will come on sooner to provide heat, but if you're driving on the highway at higher speed this may not be an issue. Now if you could dynamically vary the amount of fluid that's heated that would be good, but I think the Prius may do that any way, by only opening the thermostat as needed allowing the hotter coolant in the water jacket to gradually move into the radiator when a threshold temp is reached. If the car heater is pulling away most of the heat then perhaps very little of the hot coolant actually travels through the front radiator...... if not, I think it's the way it should work for efficiency's sake.

 

IIRC, regular ICE motors run the fluid to the heater core independent of the radiator. So even a traditional motor shouldn't let coolant flow to the radiator until it's too hot to retain in the motor's coolant jacket.

 

That's true - they're separate and don't intercept

 

of course because it's winter

 

And when there's snow on the sides of the road, that melts when warm or sunny, making the roads slicker/wetter, too. And when sand/salt is spread, you've got more slippage to the tires. And if you've got snow tires on, like I put on in the winter, even more rolling resistance.

On a side note, I usually get better highway mileage than officially listed, and lower city mileage than officially listed...it's like mine is reversed.

 

whats your typical highway speed?

 

Varies...on long trips, about 65-70, sometimes 75. Locally, closer to 60.

 

can't beat that.

 

I'd like to get this subject going again. Started it elsewhere but didn't see any responses.

I have a '13 base Prius I bought in August from my dealer--a leased car. I previously had an '08 Prius 2 for 8 years.
The '13 Prius had only 20K miles on it, and I got 55 mpg until Nov. 4th, when I brought it in for a service check.
I had the tires rotated and pressures increased for the winter.

In the first few days, I found my gas mileage dropping--finally to 46 mpg after a couple weeks.
I checked my tire pressures, and found they were slightly lower up front (mid 30s) than in the back.
I had wanted 39/37. The car did show a harder ride. I readjusted the tire pressures to 39/37,
and found the ride returned to what it had been in Aug-Oct.

Today, I brought the car into the dealer for service. The tech said mileage drops because of 1) winter gas, in pumps starting
Nov 1st, and 2) having your heater on, which uses the engine, not the main battery (!) I had raised temp up to 72, from about 65 in summer. Never realized heater could use gas! Don't recall that effect in my '08.

I said OK, I'll check it out and let you know.

I reset temp down to 65 (then on LOW--which is <65). I did get 56 mpg going about 5 miles from dealer to shopping mall--mainly highway driving. That was encouraging.

What is experience here? I didn't see this much of a mpg drop on climate change with my '08.

 

I've posted this in another thread, but I'll say it here again:

I'm in Minnesota. I drive a Gen4. I park my car overnight in a 70 degree heated lot. When the temp OUTSIDE was 70 or above, the ICE didn't need to fire up for my 1/2 mile, 25MPH commute.

With the heater OFF, and outside temp 50 degrees or lower, my Prius ICE fires up within 1 minute after pulling out of the 70 degree parking lot.

 

Reportedly the Gen2's had worse MPG when cold, an electronic thermistor hack was somewhat common DIY here. The Gen3's were better and they say Prius v was better yet, as far as warm up speed. I assume Gen4 is better. There is just a long list of reasons cold hurts: less batt power, thicker lubes, lighter gaso, higher rolling resistance on tires. But mainly your Gen2 recollection is surprising.

One thing to keep in mind, Toyota takes 50-state approach, so we have to take whatever MPG hit California wants to give less emissions in the cold. Last I looked FORD etc have slightly different vehicles in CARB states, so non-CARB states might get better cold start MPG in a non-CARB hybrid.

 

This morning it was 55°. I don't consider that "cold" at all. But I guess my car does. My engine fired up immediately when I hit the power button. (No HVAC was turned on.) It's been doing that for two or three weeks now, and my gas mileage has decreased by 7 to 10 MPG. But I'm still getting 52 to 55 mpg in the city... So no worries. I'm more than happy with that.

(To Star Caller: can you please get a new avatar that doesn't scare the sh*t out of us???

 

In addition: the car has programming controlling functions, and it relies on various sensors, one of which is ambient temperature. I'm sure, when the temperature drops: it changes the car's behaviours, maybe: raising idle speed, delaying engine shut-off, and others?

@Coast Cruiser alluded to this: with temperature drop his 2016 is no longer starting in electric-only, starts the engine immediately.

 

It's hard to avoid an mpg dip during the winter but there are things we can do to minimize it. Block heaters and blocking the grill as some have mentioned minimize it. I've been parking the Prius in the garage so that helps the leaving home part but at work there isn't a way around it. Turning down the temperature in the car has helped considerably.