Non LRR tires on Prius

[Jesse]

I just bought a 2005 Prius with 73k on the odo, it has Nexen CP641 non LRR tires. I have an ecomodded civic si that could get 50mpg with proper driving techniques.

My first tank with the Prius was only 52.5 mpg. No ecomods. I rarely used air conditioning, and stayed under 70mph, usually went 60 to 65. Had some rush hour congestion. My current tank I am only averaging 49.9mpg, staying under 60mph. Think these tires really could be costing me that much mpg? On Priuschat most owners who drive this slow achieve about 55-60mpg easy.

Thanks

[bwilson4web]

Originally Posted by Jesse

I just bought a 2005 Prius with 73k on the odo, it has Nexen CP641 non LRR tires. I have an ecomodded civic si that could get 50mpg with proper driving techniques.

My first tank with the Prius was only 52.5 mpg. No ecomods. I rarely used air conditioning, and stayed under 70mph, usually went 60 to 65. Had some rush hour congestion. My current tank I am only averaging 49.9mpg, staying under 60mph. Think these tires really could be costing me that much mpg?

We can't tell and if the tires look good, it may be a while before you put on some LLR tires. But let me suggest some things to consider:

1. Benchmark the car - without making any changes, find a relatively flat, 10 mile or longer section, and run bi-directional, mph vs MPG runs, after warming up the car for 20 minutes. It doesn't have to be the same 10 mile stretch but capture: 30 mph, 40 mph, 45 mph, 50 mph, 60 mph, 65 mph, 70 mph, 80 mph (some subset.) At 41-42 mph (indicated,) the car goes from hybrid mode when it can turn off the engine to non-hybrid mode when the engine always has to turn. BTW, data from more than one Prius owner has suggested 65 mph is an optimum cruise speed.
2. Change one thing at a time - re-run one or more of the benchmark speed runs. Be sure and record the ambient temperature and if you have the option, stay in 60-70F region.

Things to investigate:

• oil level - many of us believe it should be 1/4 inch below the "F" and NEVER over "F".
• tire pressure - find the maximum sidewall pressure on the tires and set them to it.
• temperature effects - select one or more benchmarks to repeat at 20F, 30F, 40F, 50F, 60F, 70F, 80F, 90F . . . Or what ever termperature ranges you want.

Originally Posted by Jesse

On Priuschat most owners who drive this slow achieve about 55-60mpg easy.

You may want to consider recording your fill-ups at:

• Ecomodder.com - Oh, here it is. <GRINS>
• MyHybridCar.com - a large collection of Prius and other hybrid mileage records.
• Fuel Economy - a US Government web site that is unlikely to go away or be bought.
• fuelly.com - another open web site for recording mileage.

I know how strong is the desire to do a whole bunch of stuff early without taking the time to keep careful records. The risk is you might develop a 'superstition' that some arrangement of dangling fuzzy dice and sunglasses always gives great mileage (knock on the dash three times and say one "Hail Exxon.')

You are going to be with this car for a long time, patience and you will let the car teach you what works or doesn't work. Then you'll know and be as smugly self-confident as . . . <GRINS>

Let me share some examples:

This is my first mph vs MPG chart started on the flight out to pickup our 2003 Prius and then the segments on the highway back. Notice the oil level experiment and the effect of cold weather. It also includes two sets of NHW20 (your model) Prius data at high speeds.

Treat everything as an experiment including your commuting route:

Using Google MAPs, I loaded a PowerPoint chart and plotted every practical route to and from work. Then using weekly gas fill-ups, I tested each route to find out what works and what doesn't. By weekly fill-ups, I filled the car Friday evening and Sunday evening. This kept my weekly commuting data separate from the weekend fun drives.

Again, be patient as you're going to have this car for a long time. So run the experiments, keep and more importantly, share the results ... especially here.

GOOD LUCK!
Bob Wilson

[Daox]

Your mpg sounds about right to me. Unless you live in an area that is really flat (you have "Earth" as your location, not real helpful) where you can use super highway mode a lot, your numbers sound pretty accurate. I have a lot of rolling hills in the area and I can't use SHM at all. So, I just use cruise control and smooth things out a bit here and there. I find I get 60 mpg @ 55 mph, and 50-55 mpg at 60 mph. And, that includes LRR tires and a few other ecomods.

[Bill in Houston]

tires can cost you quite a bit of mileage.

[Jesse]

bwilson, wow, looks like you are one serious driver.... Great post, actually I think I recall seeing your graphs over on priuschat, no? I understand the need for some benchmarking, but unless someone from around my area knows, I can't even think of a ten mile stretch of road around here(entire metro) that is flat. I will check the oil level, though. Never would have thought that would make much difference!

This is my current commute to work.
http://preview.tinyurl.com/3py86k2

I live in the northern metro of the twin cities. No real long flat areas, but they definitely aren't hilly either. I frequently see my instant mpg go from 70-80mpg on a relatively flat road(seems slightly downhill) and it will go down to 30mpg on the incline parts of the highways. Looks like I need to do more research, for some reason I expected to get more out of this car out of the box and my ignorance got the best of me!

I have already purchased a scangauge 2, bought it mainly for grill blocking. Before I start modding, think any of the information from that might help me with some baselines?

[bwilson4web]

Originally Posted by Jesse

bwilson, wow, looks like you are one serious driver.... Great post, actually I think I recall seeing your graphs over on priuschat, no?

Everyone is much happier now.

Originally Posted by Jesse

. . .
I understand the need for some benchmarking, but unless someone from around my area knows, I can't even think of a ten mile stretch of road around here(entire metro) that is flat. I will check the oil level, though. Never would have thought that would make much difference!

It looks like your geography has a lot of former glacial artifacts. What I'd suggest is using a Google topology view. Often river bottoms will be fairly flat and have 'roads less traveled.' Also look West and Southwest. It may be a little over half an hour drive but that solves the warm-up and in summer time ... evenings. Oh boy!

Originally Posted by Jesse

. . .
This is my current commute to work.
TinyURL.com - shorten that long URL into a tiny URL

I live in the northern metro of the twin cities. No real long flat areas, but they definitely aren't hilly either. I frequently see my instant mpg go from 70-80mpg on a relatively flat road(seems slightly downhill) and it will go down to 30mpg on the incline parts of the highways. Looks like I need to do more research, for some reason I expected to get more out of this car out of the box and my ignorance got the best of me!

Good start! Look at alternative routes, perhaps starting with the trip home when you won't be under a time requirement. What you want to find is:

• shortest direct path - speeds of 40 mph or less and well timed lights. There are likely many options so scout first.
• constant speed, no stop route - something that is safe at 65 mph or less.
• hybrids of the above - think short cuts to get below 40 mph and longer segments at constant 55-65 mph speed, especially if you accelerate down to speed on an entrance ramp (aka., gravity assist) and slow down going up an exit (aka., gravity well.) Not many folks understand terrain driving and fewer are willing to discuss it openly.

Originally Posted by Jesse

. . .
I have already purchased a scangauge 2, bought it mainly for grill blocking. Before I start modding, think any of the information from that might help me with some baselines?

Absolutly, the ScanGauge is going to help:

• ICE rpm - this is your primary indicator of engine efficiency. Good Prius Friend Hobbit has published his guidelines and I believe he considers 2,200 rpm to be the upper limit in the NHW20. With my earlier, NHW11, I use 2,600 rpm.
• ICE coolant temperature (C) - warm-up is critical to the different stages. Good Prius Friend Ken@Japan shared with us the for stages S1-4 and these are determined by ICE coolant temperature. It is so important that in cool and cold weather, I extend my neighborhood warm-up, ~25 mph, to avoid high power operation before the car is ready to be efficient in S4.
• gallons per hour - not per mile. This is your best indicator of whether or not the engine is in an efficient power band or mode.
• 4th display - any vehicle diagnostic information.

I would also recommend, when you have the time, lookup the NHW20 XGAUGE definitions. I understand there is an active community at PriusChat and CleanMPG trying to map out the definitions. Depending upon how you count them, you have 22-25 XGAUGEs and I believe having the diagnostic codes, critical engine, transmission, and battery metrics is the BEST use of the XGAUGE definitions. If you are away from home and 'something bad' happens, you have information needed to choose the best course of action. <wink>

Since you are closer to Madison than I, you might consider going to GreenCar Expo in July and seeing if you can connect with Good Prius Friend Firengineer. Part of the Chicago cabal, he is the 'Johnny Appleseed' of block heaters. I have one but only use it when temperature approach 40F. If you can run an extension cord to handle 500W, it can make your Yankee winter driving 'suck less.'

GOOD LUCK!
Bob Wilson

ps. If you run into Eric Powers, feel free to mention my name. Eric is a long time friend of Hybrids and does a h*ll of a lot of heavy lifting.

[Jesse]

Well I have slowed down this last tank. I go the posted speed limit, I have a couple 45-55mph zones where I used to go faster with traffic, and I won't go over 60mph. Over 200 miles and I am at 57.5mpg(computer). I have been setting the air conditioning at 78, especially today since it was humid with a heat index of over 100. I must be doing something right!

[bwilson4web]

Originally Posted by Jesse

Well I have slowed down this last tank. I go the posted speed limit, I have a couple 45-55mph zones where I used to go faster with traffic, and I won't go over 60mph. . . .

After a while, you'll develop an eye to spot naturally slower traffic like moving trucks or pickups towing a trailer. Use them as 'pacing vehicles' that you can follow with enough space to avoid road hazards and even any bouncing pebbles. Avoid dump trucks and earth movers, too much stuff falling off. What these pacing vehicles do is other traffic will see them and ignore your car as they seek to pass the slower vehicles. This actually reduces incidents of tailgating. <GRINS>

Bob Wilson

[HannahWCU]

Originally Posted by bwilson4web

After a while, you'll develop an eye to spot naturally slower traffic like moving trucks or pickups towing a trailer. Use them as 'pacing vehicles' that you can follow with enough space to avoid road hazards and even any bouncing pebbles. Avoid dump trucks and earth movers, too much stuff falling off. What these pacing vehicles do is other traffic will see them and ignore your car as they seek to pass the slower vehicles. This actually reduces incidents of tailgating.

I use this technique on my commute every day, Following these 'pacing vehicles' allows you to drive slower (i.e. more efficiently) without holding up traffic or creating undo road rage. Although I try to leave at least a 1 second space between me and the vehicle in front to avoid road hazards. The spacing also allows me to minimize the "inch worm" effect of heavier traffic.