"In town" driving

[hybridmel]

Okay, I am in the process of possibly getting a Prius. I live in a small town, and I do not do a whole lot of driving, just to and from work, the store, etc.

Now, I read on these forums that short trips can be a MPG killer. However, I was under the impression that gasoline does not even kick in till like 35 mpg anyway. So, theoretically, for my drives around town, I should rarely ever be using gas. Is this correct?

If that is the case, will it be bad on the main battery?

[Matt Herring]

Originally Posted by hybridmel

Okay, I am in the process of possibly getting a Prius. I live in a small town, and I do not do a whole lot of driving, just to and from work, the store, etc.

Now, I read on these forums that short trips can be a MPG killer. However, I was under the impression that gasoline does not even kick in till like 35 mpg anyway. So, theoretically, for my drives around town, I should rarely ever be using gas. Is this correct?

If that is the case, will it be bad on the main battery?

Short trips are mpg killers in the Prius, however, it is all relative to the EPA city rating for the Prius. Compared to other vehicles, the Prius will still outperform most "non-hybrid" vehicles on short trips.

For the price of the Prius, I would say a minimum of 12,000 miles driven per year is cost-effective to own one. It's a great car but if cost is a factor in your decision you should compare your cost per mile vs. buying a cheaper, used vehicle (taking into account miles driven per year, Prius mpg vs. used car mpg, etc.). If cost is not your biggest factor in the decision, the Prius is a great vehicle.

In regards to the gasoline engine kicking in at "35 mpg" I think you have the current Prius model confused with the Prius plug-in...due for release in the next couple years. The current Prius engine will run at initial start up until it's temperature reaches 160+ degrees. At that point the electric mode is available under 41 mph (using a feather foot to keep it in EV mode).

[donee]

Hi Mel,

Nope, that is not right. The gasoline engine kicks in when ever there is a demand for power beyond what the car would let the battery provide. Which is pretty low level of power, and varies depending on the situation. About 10 seconds after starting the Prius, the engine comes on. This is to lubricate everything. And for the first minute of travel the engine will be running, but wont be allowed to provide much torque to the drive train. The battery is used for this. The purpose of this is to thoroughly lubricate everything and to get some warmup of the catylytic converters. After this time, if you come to a stop, the engine will go off. But not before. As the battery is being used for torque, its best to avoid steep up hills in that first minute of operation.

The best way to get good mileage around town is to go to the farthest destination first, and do it on 35 to 40 mph roads with minimal stop signs and lights. This way the car rapidly gets through the 5 stages of warmup. After that, one can pulse and glide between the destinations back towards home. Even for medium length trips (20 miles or so) its best to start down a path that has the car rolling for the first 5 minutes.

Allot of short trip commuters use a block heater, even in the summer, to about half the warm-up time.

Electric cars have the best efficiency for short trips. The range of the electric car needed is about twice your typical trip, to avoid fully exercising the batteries to their design limit. Electric cars are not well developed for cold climates. What would be needed is a fuel-based battery and cabin furnace. Once the batteries are warmed up at like a 70 % furnace efficiency things would be great. The 2010 Prius has a feature which should help short trips - it has a coolant heater that uses the engine exhaust during the warmup phase.

[Sandy]

I do that all the time post office is 1 mile away and stores are.5 miles away still get 42 average around town, I also live in a small town

I have only used 2 tanks and my son drove it over a hundred miles and messed my average up

[Matt Herring]

Unless you need a "new" car I'd go used (Prius or otherwise) and pick up a nice bike to make the really short trips with. Save money, gas, the environment and get some good exercise too! If it's only a half a mile or a mile into town to run errands and you don't need to drive it...bike it in the summer months.

[hybridmel]

Well, I got the Prius, and it is great! I am supposedly getting twice the mileage than I was getting before.

Unfortunately, my average has gone down by the day, and I do have some mileage frustrations.

First of all, I guess you'd have to understand my town and typical drive. I live in a very hilly part of Southern Indiana, so I am very rarely on steady terrain.

I am exactly 1.5 miles from my work. There are two different possible routes to work, and neither of them seem more efficient than the other. In one, I make 5 turns with 4 stop signs. But, the turns and stop signs are fairly spread out. But, in any case, it seems like I am always dropping down to 10 mpg after every turn. The other, there is only 1 turn and 4 stop signs. However, for the first half mile there are three successive stop signs in a row, so I can never quite get up to speed. After the turn, I am on a downhill straightaway to work, interrupted halfway by the fourth stop sign. Neither route seems to work for me, and part of it may be that I am not very good at the pulse and glide thing yet.

On my old car, where I was getting 17 mpg, it took me 3 weeks to go through a whole tank, so I thought for sure it would take me significantly longer to go through the Prius. But, after a week and a half, it is on half a tank. Now, granted, the Prius tank IS smaller, and I had to make a long 160 mile drive that I normally don't, but still...I average 10-15 miles driven a day. I hope the second tank lasts me longer.

I have been looking at the Energy/Consumption on the LCD screen. According to it, I am averaging 43.6 mpg, which is way better than 17 mpg, of course, but not as high as I'd prefer. BUT, the pips seem to be off. When it fell to exactly half a tank, I did the calculations and they were off. I had driven 206 miles in it. But, if a tank is 11.9 gallons, thus 1 pip is 1.19 gallon, 5 pips would be 5.95 gallons. Multiply that by my average (43.6) should be approximately 259 miles. So, I am over 50 miles, a whole gallon, off from my average. It also concerns me that my average has been dropping by the day.

HELP!

[Betelgeuse]

Originally Posted by hybridmel

I have been looking at the Energy/Consumption on the LCD screen. According to it, I am averaging 43.6 mpg, which is way better than 17 mpg, of course, but not as high as I'd prefer. BUT, the pips seem to be off. When it fell to exactly half a tank, I did the calculations and they were off. I had driven 206 miles in it. But, if a tank is 11.9 gallons, thus 1 pip is 1.19 gallon, 5 pips would be 5.95 gallons. Multiply that by my average (43.6) should be approximately 259 miles. So, I am over 50 miles, a whole gallon, off from my average. It also concerns me that my average has been dropping by the day.

HELP!

The answer to this is simple: the tank can't actually hold 11.9 gallons and the pips do not disappear in a linear way. In other words, even though there are 10 pips, it's not like each of them represents 1/10 of the tank. As many have noted, the first pip takes a long time to disappear.

(BTW: I'm assuming that you have a <= 2009 Prius in the next paragraph. If not, please ignore)

On the other point, your Prius is equipped with a rubber bladder in its gas tank to help minimize emissions. What this means is that, although your gross tank size is 11.9 gallons, you'll almost never get that much gas into the car. People routinely max out at 10, 9, or even 8 gallons. As you will find out in a few months, the rubber bladder is much less pliable in the cold, so your "winter tank" will be even smaller. It's something that most of us have learned to live with. Don't try to guess how much gas is left in the tank; just fill up when the gas gauge gets down to 2 pips or so.

[Matt Herring]

Hybridmel,

Good to hear you love your Prius! And, you are getting significantly better mpg than you did in your old car so that's a big bonus.

In regards to your short trip to work each day you are going to have a tough time getting up to temp and able to use all of the options the Prius offers in terms of maximizing mpg from an engine/EV standpoint.

In the warmer months you might be up to temp near the end of your commute but in the winter I doubt you will come close to that. If you can get into EV mode at some point of your trip that will help you raise your mpg and you won't be using that much battery power to do it that you won't recapture in the brakes over 1.5 miles. To combat the warming up issue you could invest in an EBH (engine block heater...$40-50) to have your car nice and toasty prior to starting. This might get you up to temp very quickly or at least increase your mpg over the 1.5 mile commute.

I'd advise getting familiar with pulse and glide (and against the advice of some on this site...neutral coast) to raise your mpg. Make sure your tires are at or near max psi. Look into installing a simple grille block with foam pipe insulation (not recommended in 75+ degrees ambient temp).

Short trips are mpg killers in the Prius (and any car for that matter) so if you are running errands I would recommend leaving the car on if you just have to run in a store quickly so you don't have to go through the Prius start up cycle when returning to your car (this advice is only advised if your car is already up to temp when you stop at a destination and won't be in there longer than a few minutes). Make sure you power down all electronics in the car (lights, radio, AC, Ipod, etc. before you exit the car to run in a store/shop) to save on the battery.

[ksstathead]

Lots of mpg help at cleanmpg, too. See general hows and whys article by xcel, then his Prius II article.

I did a chart of the warmup cycle of the Prius II posted in the knowledgebase here at PriusChat. Contains lots of links to guide you to more complete discussions.

[Shawn Clark]

Effectively it is more like an 8-10 gallon tank when going from full to flashing pip--and this can be highly variable in the same car from fill up to fill up. (My last fill inexplicably went over 10 gallons...about a gallon and half more than the MFD mileage indicates it had used. After so many 8 and 9 gallon fills I'm thrilled to get some respectable tank capacity!) The combination of bladder and digital gauge makes the fuel level very uncertain compared to normal gas tank/gauge combinations.

Think of the pips like you would the markings on a normal analog gauge. On the analog gauge when the tank is full it is usually noticeably above the full mark. Mine typically have as much as 1/8th tank above the full mark. And when a tank with a working analog gauge is empty it is usually well below the last mark--how much I don't know as I've never run out in a vehicle with a working gauge despite getting within a few tenths of rated capacity in them. In the case of the Prius, the last mark is the flashing pip...somewhere in the 1 pip range. You have NO indication below the flashing pip and the bladder makes the tank unreliable/variable below this indication so fill ASAP when the flashing pip comes up. People have gone empty at 2 pips. If that happens then the gauge needs calibration or something is odd with the tank anyway.

From what I can tell the calibration of mine might have as much of an 1/8th of a tank below that flashing pip. BUT because of the bladder there is no way to know and it might be right at empty, and/or the pump might not be able to suck that last amount of gas out.