Short Tripping or "mini-tank" mileage

a lot has been discussed over the merits of the "average speed" verses MPG over various time periods. it has become pretty clear to me that the average speed over an entire tank of gas simply covers so much time as to be really useless. so i decided to track mileage over a well used route (work commute) to see how well the Pri handles short trips.

background: trip about 7 miles on way. relatively flat. some hills and valleys but start and end point elevations not a lot of difference. 11 traffic lights, 2 stop signs going, 3 coming. 58% 40 mph, 33 % 35 mph, 9 % 25 mph. Trip B reset for each leg.



morning commute; 5.30 AM very little traffic, lights on. cold but heat not used at this point.

afternoon commute; 4.30 PM. heavy traffic with high possibilty of stop and crawl traffic. daylight (will be dark after time change and will repost additional data for winter)

data points

miles; MPG; average speed; OAT; Delta SOC

edits; added stats after grill blocking. this is last set of numbers using summer formula gas

EDIT : winter is here. an obviouse drop in mileage seen. some symbols on lines for additional notes concerning conditions

*= wet roads or light rain
**= heavy rain and/or standing water on roads
D = extended defrost or ice scraping usually in morning only this early in the year

morning

7.1; 56.1; 32; 61; 0
6.9; 54.2; 29; 62; +1
7.0; 53.5; 30; 66; +2
7.1; 57.1; 31; 65; 0
6.9; 53.9; 29; 57; +1
6.9; 55.3; 32; 57; 0
6.9; 50.1; 32; 46; +4
7.2; 56.3; 30; 44; 0
7.1; 52.2; 28; 45; +3
7.1; 54.3; 27; 45; 0
7.0; 53.3; 31; 51; +2

7.3; 55.1; 26; 43; 0
7.1; 51.3; 28; 45; +1
7.1; 58.8; 31; 50; +1
6.9; 52.3; 33; 39; 0
6.9; 48.8; 028; 36; 0 ** windows iced up, had to run defrost a few before driving
7.1; 54.3; 26; 42; 0
7.1; 51.9; 26; 42; 0
7.1; 48.2; 28; 32; +1
6.9; 51.3; 26; 43; +1

7.1; 53.8; 28; 51; +1
6.9 ; 55.9; 31; 52; +2
7.1 ; 54.6; 28; 54; 0
7.1; 51.9; 27; 54; 0 ...**
6.9; 53.2; 29; 50; 0 ....*
6.9; 49.6; 29; 36; 0 ...D
6.9; 54.6; 30; 54; 0
6.9; 49.4; 27; 36; 0 ...D
7.0; 53.5; 28; 57; 0 ...*

Afternoon;

6.9; 65.1; 21; 69; 0
6.9; 68.1; 23; 72; -2
6.9; 72.1; 20; 75; -2
7.0; 63.7; 27; 70; 0
7.0; 64.1; 26; 69; 0
6.9; 63.2; 25; 70; 0
7.0; 63.2; 20; 64; 0
6.9; 64.0; 28; 66; -1
6.9; 63.1; 23; 74; 0
7.6; 71.0; 23; 82; -2
7.0; 62.7; 23; 76; 0

7.0; 59.6; 23; 59; 0
7.0; 63.4; 25; 63; 0
7.0; 60.7; 25; 61; 0 ** opposite direction**
7.0; 61.1; 24; 63; 0
7.0; 64.9; 27; 66; -1
7.0; 60.6; 18; 66; 0
7.2; 62.7; 25; 57; -1

7.0; 56.2; 23; 60; 0
7.0; 60.0; 27; 60; -2
6.9; 57.3; 19; 57; 0
7.0; 55.8; 16; 57; -1
7.0; 59.5; 20; 60; 0
7.0; 56.1; 26; 56; 0
7.2; 54.7; 15; 50; -1

ok. so there it is... kinda started this late so the dont yet have the temperature range i was hoping for, but then again, it doesn't really seem to matter.

what does matter is the SOC. there is a major penalty for short trips when SOC is below 6. because of road construction (which is happening on that short north-south jaunt on Yelm Hwy) i frequently have to detour which lengthens the percentage of the 25 mph commute. this basically runs my SOC down. i actually discarded some of those because they were way out of the data range. some detours took me to nearly 8½ miles and involved sitting on the road while construction equipment cleared up to 15 minutes at a time.

will continue this latter to see what effect temps have in winter with and without grill blocking

http://maps.google.com/maps/ms?ie=U...81,-122.901993&spn=0.013847,0.027595&t=p&z=15

**edit** fricking Google!! ok. i guess we try something else for maps

 

show off!!

 

well this chart was a restart because of the large discrepancies in mileage. i even did a couple reverse trips where i drove to work on my day off in the afternoon to see if direction made a difference (it didnt) and it took me a bit to realize how much of an impact SOC had on the short trips.

but then i noticed the difference in SOC which was aggravated by the construction. because of it, i was detouring either on 54 th ave coming into my development which basically meant over a mile at 25 mph which meant a pretty low SOC at end of trip but high mileage which i lose the next day. the other detour option was turning at college/rainer to ballustrade then a cut over which used EV since balustrade is all 25 mph as well.

a couple of times when bombing around town on errands, i did a reset to see what short trip mileage is with no warmup. seens like i am settling around 80 mpg...not bad

 

LOL!! oh man, WOW really have time on our hands.

ya, if you look, the 50 mpg trip was the next morning after the 70 mpg trip. i did the detour thru Balustrade. my SOC parked and the next morning was 2 bars. with that short of a trip, it took something like 5-7 minutes to get into good mileage when normally it takes 2-4 minutes. doesnt sound like much, but on a trip that is only around 13-14 minutes in length, it makes a big difference.

 

for a real understanding of what affects your mileage, it might be hard to evaluate a tank the consists of several dozen trips of varying lengths, traffic densities and weather conditions stretching over several days or weeks.

any error you make will be magnified. i do not advocate not keeping LT stats. in fact, i greatly encourage it and post mine in my signature in order to encourage others to do so.

also, when it gets right down to it, its simply more knowledge. now gathering knowledge does require work and a question of evaluating the worth of the data verses the time it took to gather it is a question i am not going to address

 

well, it might not be. but i only spend less than a minute a day gathering the data. less than a minute archiving the data. what the heck, i have 3 80 GB hard drives plus a 500 GB external. one drive is about 70% full, the others less than half... might as well do something with them

but the real point is, i cannot determine the worth of the data before i gather it. its only after i have collected it, examined it, posted it here for others to see, will i be able to determine if its worth anything.

as far as value, i enjoy it. i have other things that occupy my time that provide me enjoyment at a much higher cost. i have my RC Car habit which i put about $1000 a year into it and still cant win a race!!

 

well, i think you if the trip is short enough. overall, on a tank, you would see nothing. but on my short trip records, i was seeing wild swings in mileage and always had to do with gaining or losing battery bars. one the one tank i had, it was 71 mpg, granted a bit longer due to construction detour, but also lost a few battery bars. iow, more power from battery to get the high mileage.

the next morning, i take off with only 2 bars, get to work with 6 bars, but mpg is 5 mpg below normal so have to assume that 5 mpg drop was caused from adding 4 battery bars.

i actually have a much greater sample but because of construction delays, i tossed out a few because their numbers were way off the norm....but basically, i was doing 54-56 in the morning, 63-64 in the afternoon.

now, the weather has changed. afternoon temps 10-15 º cooler. also started grill block, so will be posting another set of numbers in a few weeks for comparison

 

well Bob, you add a weight sensor that does not supply power until a certain value, low enough to overcome calibration issues, but high enough that only the severely obese would be in danger (lol...sorry, but had to add that in there... these could double as shock stations for heart attack patients...oh nm...skip that last comment)

but seriously, considering the parking abilities of many people, this sensor would have to be smart in many ways, so accidental shock i think could be worked out well enough

 

**edit to OP**

posting another set of numbers. the additions will be in a diff color and posting these because they are during colder weather but since its on a tank that was filled Sept 15th, it was still on summer formula gas. this was also start of grill block at 100% top and bottom. (probably going to 75% top block due to concerns over inverter temps)

i just got gas yesterday which is first winter tank formula.

 

added to OP...

this winter formula gas, mileage definitely lower
color in red