Factors affecting MPG

[donalmilligan089]

some times ice has to recharge low HV hattery

[etobia]

Originally Posted by donalmilligan089

some times ice has to recharge low HV hattery

What does ICE mean?

Also, the different battery colors.... What do they mean? Should I take every opportunity in a downhill and approach to a stop light to use B instead of breaking to recharge the battery?

[PaulHS]

Originally Posted by etobia

What does ICE mean?

Also, the different battery colors.... What do they mean? Should I take every opportunity in a downhill and approach to a stop light to use B instead of breaking to recharge the battery?

ICE is the Internal Combustion Engine.

The different battery colors are just visual cues to make it easier to read the state of charge (SOC) of the traction battery. For all intents and purposes, green is full charge, blue is the most typical operating range and purple is low battery. The purists here will disagree, but I'll let them explain it their way.

The "B" setting is not very useful. It's primary function is for slowing the car when driving down steep hills or mountainous terrain. The almost universal opinion here is not to bother with it.

Hope this helps

[resoh02]

Originally Posted by BDDave

Not having your headlights on during day light hours is a safety hazard and should not be done! "Lights on for safety" should be your moto. It's foolish to think it saves fuel to have them off.

I personally think that running lights are rediculas anyway. The only thing it does is burn the light bulbs sooner. Have there been any information that it actually cuts down on accidents? It would be a better rule that everyone turn on headlights at dusk!!!!

[resoh02]

Originally Posted by etobia

I'm a frustrated owner of a Prius bought Jan. 2008. Live in upstate NY. Winter driving on short trips as low as 32 mpg while achieving 50 mpg. on long highway drives during winter.

Typically achieve better mileage over the road than in the city! (10-20 mpg)

Driving example: I took a Toyota mechanic on a slow ride around the building and the lot. Guess what: the first two times the car was in 100% electric. Third time electric wouldn't kick in completely and showed 25 mpg! He couldn't explain why it was doing that cause nothing about the driver/driving environment changed. By the way.... the weather was optimum: 70 degrees, no humidity so no extras running.

Seems to me that the car should be able to maintain all electric in a parking lot. Same with driving on a road that is perfectly flat with a few stop lights. If it uses gas, it should be minimal and then "catch" the electric mode. the thing just won't do it enough.

This summer, best I've done around town is 44 mpg. Machine has 16,000 miles on it.

Seems like a manufacturer issue as we have tried to employ all techniques.

Any thoughts on what I need to do? How can I get the dealership to look into it further instead of always pushing it off to: it's to new/read the driving tips/etc.

They insist there isn't anything wrong with it because service lights aren't coming on.

One thing that can really kill your mpg is the cruise control on especially in hilly terain. I would call the toyota complaint department and take the problem to a district manager.

[BDDave]

Originally Posted by Shawn Clark

It's not a safety hazard. It is normal, same way I've driven for decades.. Saves a little less than a mpg in the Prius. You can choose to do as you like, but I'll take the nearly 2% fuel savings, thanks.

I'll take safety over MPG every time.

[DeadPhish]

Originally Posted by etobia

I'm a frustrated owner of a Prius bought Jan. 2008. Live in upstate NY. Winter driving on short trips as low as 32 mpg while achieving 50 mpg. on long highway drives during winter.

Typically achieve better mileage over the road than in the city! (10-20 mpg)

Driving example: I took a Toyota mechanic on a slow ride around the building and the lot. Guess what: the first two times the car was in 100% electric. Third time electric wouldn't kick in completely and showed 25 mpg! He couldn't explain why it was doing that cause nothing about the driver/driving environment changed. By the way.... the weather was optimum: 70 degrees, no humidity so no extras running.

Seems to me that the car should be able to maintain all electric in a parking lot. Same with driving on a road that is perfectly flat with a few stop lights. If it uses gas, it should be minimal and then "catch" the electric mode. the thing just won't do it enough.

This summer, best I've done around town is 44 mpg. Machine has 16,000 miles on it.

Seems like a manufacturer issue as we have tried to employ all techniques.

Any thoughts on what I need to do? How can I get the dealership to look into it further instead of always pushing it off to: it's to new/read the driving tips/etc.

They insist there isn't anything wrong with it because service lights aren't coming on.

It is not useful to try to 'outthink the computer' that controls the drive system. Just allow it to do what it does best. When the Prius was first new it was thought that crawling away from a light or a stop sign was the best way to use the e-motor and not to use the ICE.

It was found later on that just accelerating normally and smartly then allowing the captured kinetic energy in the vehicle to drive/coast the vehicle was much more fuel efficient. The 'pulse and glide' was discovered.

As to trying to keep the engine in electric mode...why bother? Just let the algorithms do their jobs and forget about it. IMO it only increases frustration for a nominal gain in FE.

The one thing that can increase FE dramatically is eliminating short trips as you've noted. Short trips have a 20-40% deleterious effect on fuel economy - especially in Upstate NY in winter. Combine short trips as much as possible into longer trips.

That will save a lot more fuel than actively trying to keep the e-motors on at low speeds. I doubt very seriously if there is anything wrong with your vehicle.

A post I wrote two years ago...

Now that winter is fully here you might want to take into consideration some of the following factors which can often be outside your control entirely. These generally act to decrease your fuel economy. But, hey, it's the same for every vehicle on the road as well. For some it's even worse.

Factors affecting your FE ( and everyone else's also, btw ) in decending order of importance...
1) Towing anything is a huge penalty possibly as much as a 50% reduction in FE
2) Lots of weight in the vehicle, passengers cargo etc. ( EPA tests are done empty ) deduct up to 20% from your 'Norm'
3) Short trips under 10 min - deduct 20% from your 'Norm'
4) Snow, Rain, sleet - deduct 15%
5) Strong head wind - deduct 10%
6) Cold weather - deduct 5 - 10%
7) High speed driving 0ver 70 mph - deduct 5 - 10%
8) Many starts from a dead stop ( going from stop sign to stop sign to stop sign ) - deduct 5 - 10%
9) Terrain - fortunately 'what goes up..' usually this balances out on a RT
10) Winter fuel - deduct 2 - 5%
11) Low tire pressure - ? How low

Now these are cumulative, so short trips ( -20% ) with a lot of stops ( -10% ) in winter ( -7% ) on slick pavement ( -15% ) can result in as much as a 40 - 50% loss from your personal 'Norm'.

[Celtic Blue]

Originally Posted by BDDave

I'll take safety over MPG every time.

The "illusion of safety" is a more apt description. There are times I turn on my headlights, but not in good weather & lighting where I'm not concerned about visibility.

I watched today for those with DRL's or their lights on, just to see if I could perceive any difference in spotting the vehicle in normal daylight. The lights are so dim that it made no difference.

[Fibb222]

Originally Posted by resoh02

Have there been any information that it actually cuts down on accidents?

I hope there are studies. DRLs are mandated on all vehicles in Canada - have been for several years. Hopefully, not for no reason.

[chrisky]

Originally Posted by Fibb222

I hope there are studies. DRLs are mandated on all vehicles in Canada - have been for several years. Hopefully, not for no reason.

Just for anyone's information, this is what I found on Transport Canada's website, and I quote:
" Dec. 1/89 Canada became the 2nd country after Norway to require daytime running lights on all new passenger cars, multi-purpose vehicles, buses & trucks manufactured for sale in Canada in order to increase visibility & reduce collisions. The combined effect of this regulation & the voluntary use of DRLs - in vehicles not previously equipped- has been an estimated 11.3% reduction in daytime collisions involving 2 vehicles travelling in different directions."
So it looks like it is effective, I just don't know if they are still keeping stats on this. Would have to research it further.