Difference between warmed-up and cold-start

I've been averaging 4.5L/100km (52 mpg) these fall days as opposed to 4.2 (56) in the summer. My trip is 16 km/ 10 miles one way, with lots of traffic lights and slightly up and down hills/bridges.

This morning I drove my son to the airport real early and came home to pick up my wife for the normal everyday trip to work. The airport traffic was so bad that it bump the FE to 4.7/50 so I reset the trip B settings b4 the normal trip.

I guess the ICE was fully warmed up by the airport trip and I got 3.8L/100km / 62mpg for the same morning trip. Weather is actually much colder it was only 9 degrees Celcius. Same driving style/habbits as b4: always gunning it to accelerate in PWR mode right up to 10-15% above speed limit, set to cruise control and look far ahead to start coasting as early as possible without impeding traffic.

I wonder how a warmed up ICE makes such as big difference! 4.5 / 3.8 is 18.4% different!

Can anyone who have installed the engine block heater tell me how much does the block heater help the mpg? I am seriously considering getting it installed. Thanks.

 

Thanks I get that. I'm just surprised by the BIG difference (even for summer I imagine). I also wonder if the block heater can really negate the whole warming-up waste or just partially and that's why I'm posting to ask. If it does then the $350 block heater option (pricing fromToyota Canada web-site) doesn't seem that expensive anymore.

I see that the PC shop does sell the block heater for $59 but I can't order it to ship to Canada? And what about the trouble of installing it? Is it worth the extra $290 to get it installed by the Toyota dealership?

 

On another note I kinda remember that the Canada EPA rating for the Prius was 3.7 L/100km city and it was tested after the ICE was warmed-up (correct me if I'm wrong). Now it doesn't seem to be a number so out-of-reach or out-of-touch with reality.

Maybe all these Prius owners' complaints about unable to match the EPA numbers can be easily fixed by installing the BH?

If the BH helps so much even in summer why didn't Toyota made it a STANDARD FEATURE and write it down as a standard practise in the user's guide? Toyota, are you listening?

I imagine this is universally good for all cars and not just for the Prii. Why the governments not promote/mandate this for all cars. Imagine if ALL cars gets 5 mpg improvement by simply plugging it in for warm-up. And it doesn't strain the electrical grid since most cars would be plugged in during the night. It's such a cheap solution to such a relatively big improvement!

 

And spend $100 on gas and another $200 on hotel + meals? I might as well get it done by the dealership. Thanks but no thanks

 

Timer is no big deal, thanks for the tip.

rough calculation:

BH electricity usage 400W? x 2 hrs = 0.8 kwh x 6 cents ~= 5 cents each day = $18 / year

4.5 - 3.8 = 0.7 L/100km worth roughly $0.7/100km in Canada. For the typical 20,000 km/year driving that leads to $140 savings / year. Say the BH only saves 1/2 of that makes it $70 / year savings.

$70 savings - $18 electricity bill = $52 / year net savings.

Darn it, I need 7 years to recoup the $350 cost for installing BH!

Still, I think it's worth it for the environment 'cause the warming-up must be spewing a lot more toxins.

Oh shoot, does a BH last 7 years long?

 

I tested one more time this morning. I reset trip B right after the warming up when ICE stopped. Then the whole trip worked out to be even better @ 3.7 L/100km. probably due to lighter traffic. Trip A is now down to 4.4 so pretty consistantly warmed-up fuel consumption is lower than cold start by 0.7L/100km.

Does the EBH heat it up to more than 20C in 2 hrs? Maybe if we test with EBH heating for different time periods and make a chart of heating time against FE difference, and then we could determine what's the heating period that yields the optimum net savings. Maybe if it's 1 hr then it's even more worth it.

Hmm, time to give the dealership a visit.

 

Happy to report that I'm now the owner of a EBH of Toyota original parts, installed in my Prius, of course. I'm going to start using it and record the impact of mpg versus period of time plugging in the EBH. Will keep you posted when I collect enough data.

Last week I called the dealership's maintenance department and the girl quoted $350 for installing the EBH, just as the Toyota Canada's website listed. They didn't even have stock and have to order it and scheduled the installation for today. Final price came out $90 parts and $153 labour = $243, saved me over $100 as compared to the original quoted price of $350.

Hmm, I wonder why. Maybe because I threatened never to come back for maintenance for the next 15 years over the argument with their maintenance manager whether the 2010 Prius requires 0W20 synthetic oil?

I took the opportunity to ask them for the free oil change even though my Prius just hit 5000km, not the 8000km (5000miles) as Toyota original maintenance schedule listed. I wanted to get rid of the break-in gunk sooner. THEY REFUSED to use 0W20 synthetic and only agreed to use 5W20 non-synthetic, or I have to pay for the difference in price! The maintenance manager also said that it's not good for the engine to put synthetic oil so "early"; and that they have serviced a lot of Priuses and they know what they're doing.

I pointed out the specifications in the 2010 user's manual asks for 0W20 and the only 0W20 oil is synthetic, and even the original oil that came with the brand new Prius from Japan was already 0W20 synthetic. He went inside for 15 minutes and came out apologising saying I was right and that he mistakened my Prius as a 09 model. Do they ever READ their own Toyota's documentations? Gees!

Anyways he finally agreed to use synthetic at no extra cost to me. I also have to remind them not to fill in the whole 4 bottles of oil as the Prius only take less than 4 litres. I checked the oil afterwards and it was right in the middle of the 2 dots. Wow, the 0W20 oil they put in is AS CLEAR AS WATER, with no hint of brown colour whatsoever! Is that normal? I hope they didn't just put in some snake oil?

I read somewhere here that Toyota US had changed the requirement to 10,000 miles = 16,000km between oil changes. Does anyone know if that also applies to the great white north Canada? Maybe the extreme -20C cold winters make it count as "severe" driving conditions and we still have to keep changing oil every 5000 miles/8000 kms?

 

Thanks. Even nicer 2 days using the EBH:

1st day, 20c, plugged-in 2 hrs, FE dropped to 4.0 (from 4.4 L/100km)

2nd day, 12C, plugged-in 1 hr, FE dropped to 3.8!

Looks like I can pay it off in much less than 7 years!