Help me with my commute

First, I'm relatively new with my 2011 Prius, only having it for 10 days as of this writing, so I'm sure my technique will improve a little. During that time, I've been averaging about 53.6 mpg, but I feel as if I can do better. I've set 54 mpg as this "magic number" that I'm aspiring to, but if I ever reach that, the number will probably rise to 55 and so on ... (As an aside, if I just set the cruise control while on the commute I'm about to describe, I get the same mileage as I do when I'm working on hypermiling, so I don't know if it's worth the effort with this route). Please help me improve my numbers

My daily commute is around 15 miles. About half of this is a hilly and curvy road. The PSL on that portion is 55 mph, and it is a two-lane (one lane in each direction) road. At least one of the hills are so steep that if I DWL, I'll lose between 15 to 20 mph from the bottom to the top; that's with the HSI "pegged" right before the power section of the line. I can maintain speed, or at least lose less, if I go into the power area. Additionally, there are several curves at the bottom of the hills where I must brake down to around 40 mph to safely negotiate the curve.

Finally, it is well-trafficked road as well, so, while observing the speed limit, I may have 10 cars piled up behind me, which makes me nervous.

One last thing. I know a/c hurts my mpg, but this is south mississippi, where the humidity is so high that you even need a/c in winter, so it's going to be on if I'm in the car. (Heat index today is 110).

 

Sorry about not posting the questions first. Here goes:

- Have you read This Thead Yet?

Yes.

- What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)

By trip computer, I'm averaging 53.6 mpg.

- What fuel economy are you expecting and why?

Right now, I'd be happy with 54. Why? Because I'm competitive and I see all these people with mpg in the 60's or higher in their sigs.

- What are the approximate outside air temps?

In the high 70's during morning; mid to high 90's during the afternoon commute. Don't know if it matters, but humidity is in the high 90%'s.

- How long are your trips?

I plotted my route on toporoute.com, and it got 17.86 miles.

How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here)

I assume it's the original battery, and the car entered service in december of 2011. I just bought it about 10 days ago. I have yet to check the voltage of the battery, but I suspect it may soon be time to change it. I'm losing 1 or 2 bars overnight with the car just sitting there.

Have you had your alignment checked? Any pulling or abnormal tire wear?

No alignment checked and no issues noted.

- How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving?

It's about half and half. In the "city" part of it, the PSL is 45 and the "highway" PSL is 55. During the first part, it's possible for there to be a lot of stop and go. The traffic lights are not synced at all, and it is possible that I'll have to stop about once a mile before I get to the highway portion of my commute.

- What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)

Rolling and steep hills. Overall, there's a 200 foot increase in elevation from home to work with a mean grade of 0.2%. Attached is a graph of elevation vs distance.



- What are your tire pressures?

Haven't checked since I bought the car.

- Is your oil overfilled? (i.e. above the full mark on the dipstick)

Nope.

- Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)

07 Kia Optima with the base 4-cyl engine. It never did this commute, so I can't compare.

- What region/state are you in? (if you haven't set your location)

Hattiesburg, MS (about 1 hour north of the gulf coast)

- How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?

I'm following the "guidelines" on P&G. I have the HSI up to the edge of power on the pulse, and I have no lines indicated on the glide. I brake very gently. If I see a stop coming up, I'll exit my glide and enter regen from the "engine drag." As I get closer, I'll use regenerative braking if needed, but I never fill up the regen portion of the HSI.

- What modes are you using, if any? "normal", EV, power, eco?

I started out on the commute on eco, but I have discovered I personally do better on normal, so that's where I keep it.

- Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?

No. The mornings are so warm that the ICE is usually warm before I've gone .1 or .2 of a mile.

- Are you driving using D or B mode?

D

- HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?

In the mornings, I usually have the AC set on 76. Start off on normal AC and switch to max after I can detect that it has cooled the interior. Usually, in the mornings, I just need it to get the humidity out of the air. The external temp is pleasant to me. Same in the afternoon commute, although the external temp is in the 90's by that point.

- Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15).

Factory tires and wheels; the 17" ones.

- If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute?

N/a

 

Checked the tire pressures, and they were at the recommended pressures. I increased them to 42 front, 40 rear.

 

Right before I left work today, a thunderstorm came through and cooled things significantly. The outside temp was 72 on my commute home. I didn't use a/c, and mpg went up to 56.8.

 

Yes it was. Checked again this morning just to make sure, and the pressure was the same.

 

Finally made it to 54, and got all the way up to 54.2 mpg. I think what made the difference was the temperature was lower because of rain, and I could leave the a/c off, or if I did run it, I used it intermittently, turning it off when I got comfortable and leaving it off for several minutes before turning it back on for a minute or so.

 

Thanks, I hadn't thought about that.

 

I actually work in a different city from where I live. There are three routes I can take. Two are on state highways and one is a mix of interstate and state highway (it's the longest of the three). I've been taking the state highway route with no traffic lights in it (but stop signs), but my project for the rest of the month is to spend a week taking each and seeing how mileage compares.

 

Can you elaborate on what you mean by zig-zagging?