Car cold: Driving tips for short distances especially when its cold outside

try to accumulate trips, drive to furthest and work your way back. other than that, take heart that your still getting better mpg's than most other cars. have you considered a pip? great for 12 miles r/t in this weather and 16 in summer.

 

Pip= Plug-in Prius. Try a crankcase heater...

 

Gloves and Jacket.
Keep the cabin heating OFF.

The harder part can be how to handle a foggy windshield. Try very hard to not rely on the defroster. I scrape the windshield before I start up the car, and do no breathe on the glass when I am driving. If you are in a dry climate, crack a window open.

 

No doubt mileage drops in cold weather and with short trips. However, what I found is that even with the drop in mileage, I'm still way ahead of what my Toyota Matrix would have gotten for mileage under the same conditions. Remember, it's not just Prius mpg that suffers, but ALL cars' mpg suffers in cold weather and with short trips. So if you're not getting as good a gas mileage as you'd like in your Prius, remember... it's still waaaaay better than that guy driving the Nissan Altima, Toyota Corolla, or that Cadillac Escalade.

 

This is a good topic...we are doing a lot more short trips too.
Some other ideas:

> There is a themistor hack posted somewhere to fake the car into thinking it is heated up for better MPG.
> If you are stopping for short stop, don't turn the car off if you don't need to
> Front grill block

I am thinking, but not sure about this, the lower Prius MPG at start-up in part has to do with CARB requriements for low emissions during the cold engine period. But those of us NOT living in CARB states are paying the price for this feature we do not really want. But we got it anyways because Toyota chooses to sell CARB certified cars in all 50 states. So if you bought a FORD hybrid, you can probably get a non-CARB version that may be better MPG during this cold engine period, some say. Of course, I don't know where the OP lives.

 

I have been researching this since the Hawaiian Thread. Seems both Ford and Toyota carry different certifications for CA and TX. See the screen grab from Fueleconomy.gov.

I have no idea if the Prii are built the same, just "certify" differently for legal purposes.

CARB states get PZEV certification, and everyone else gets Bin 3.

 

A couple of data points:

• 45-55 seconds catalytic converter O{2} sensors start working - during this time, the engine runs using a look-up table for fuel trim. The literature suggests a rich mixture is used to accelerate warm-up.
• Time to 40C coolant - during this time, the engine will not shutoff. A block heater or thermistor hack can save a couple of minutes.
• Time to 55C coolant - if the heater is on, the engine will not shutoff. The thermistor hack can save this time.

Other mitigations:

• 25 mph route with maximum use of "N" - keeping the engine in 'idle' mode to the maximum extent possible. Shift into "N" when stopped.

Bob Wilson

 

Yes I agree with you I don't undertand those designations, but I think Trollbait understands that stuff if he sees this please advise. He basically says if you order a Prius there is only one car to order. If you look at EPA fueleconomy.gov site I believe yes FORD has non-CARB versions listed, possibly with different MPG ratings, I cannot recall.

 

As BobWilson says, the Prius operates along different lines than normal when it is first started, and until the engine reaches predetermined temperature thresholds. If you have the opportunity to not push the engine* during the 1st mile, that helps a lot.

IIRC my car is in ECO-mode all the time, meaning the fuel pedal gain is small.

*My first mile is about one mile to exit my neighborhood. I pretty much rely on the (increased) idle speed of the engine and battery power during these first 2-3 minutes to move the car. I then drive with the engine continuously at 1-2 bars into the power range until the engine is heated up enough to let me glide at will. Done this way, I can still hit 50 mpg over a 4.5 mile return route when the temps are in the 30s F.

A lot depends on the routes available to you; and as I mentioned earlier, if you have a fogged up windshield then forget about fuel economy and deal with the safety issue.

 

We're heading out the door in a few minutes. A couple of hours back we plugged in the block heater. Ambient temp here is a (balmy) +7C right now. By the time we've gone a 100 yards, coolant temp (readout on ScanGauge) will likely be around 35~40C. By the first stop sign or red light, we more-n-likely have engine shut down.

 

Under the emission rating on the attachment and Fueleconomy.gov site is the engine code. This designates what engine and emission equipment the car has. The Prius and the Ford have the same engine code regardless of which state. So the one bought in Texas has the same equipment as the one bought in California. The different certifications, if they are actually different, are for warranty and other financial reasons. CARB and the feds have different labels for emission ratings. IRRC, bin 3 and PZEV are close in actual emission limits.

Lean mixes burn hotter, and full throttle usually enrichens the mix for extra cylinder cooling. The rich mix at start up is most likely to reduce NOx emissions.

As to the OP, has others have stated, you need to get the car to warm quicker in order to improve fuel economy. Otherwise the Prius will spend most of the trip in the warm up cycle. A block heater is the best method. For a lower investment, I used a cardboard grill block with some insulation placed around the engine with cars in the past.

 

some ideas below
1) + Block the grille (search here at PriusChat) - have to track the temperatures and remove in Spring
2 + Pre-heat the engine (Block heater, $55 at PriusChat store) - have to remember to plug in/ disconnect; cost of electricity; electric hazard
3) + Preheat cabin/defrost windows using 110V household heater connected to power outlet - possibility of fire, cost of electricity; electric hazard

my 0.02

- Alex

 

Yeah, grill block too. Right now I'm blocking 50% of lower opening. I never block the upper, since the inverter radiator is in that area. You could block up to 50% of upper, but I prefer to play it safe. Our ambient temps are around +4C to +12C the last few weeks, pretty sorry excuse for a winter.

 

Interesting.
How much reduction are we talking about? Wouldn't the electric motors have to pick up that slack? AND doesn't that delay warmup?

 

Working on another problem, I found some cold-start data:

• 11.3 C/min initial warm-up to 40 C, with heater off, 3 min. 6 -> 40 C
• 3 C/min warm-up to 55 C, with heater on, 6 min. 36 -> 54 C
• ~8 C range for heater ON, engine thermal cycling

Determine how many degrees C from outside temperature to 40 C. Divide difference by 11.3 to get initial 40C warm-up. Add 6 minutes to engine off with cabin heater on. So if freezing, turn on heater and wait 10 minutes to get in car. If -12 C (10 F), about 11 minutes or enough for a microwave heated cup of chocolate.

Bob Wilson