Frontage roads vs the Freeway

bomber991 · #1 02-03-2008, 06:30 PM

So my commute right now is a 10 mile trip from my house to the Park & Ride, where I then ride the bus for an hour with homeless people and regular people that don't know that soap is require for showers to work properly.

Anyways, right now the majority of the 10 miles is on a freeway. I've been doing 70mph to 55mph glides on it, but I really notice how quickly the car slows down in the wind. Scangauge on average has been telling me 28mpg even on the trip there.

So I'm going to try taking the frontage roads instead tomorrow. I leave the house at 10am so there isn't much traffic on the roads, but there is enough on the interstate to where I can't go lower than 55mph. On the frontage roads I should be able to do a 60mph to 45mph glide with no problems. Plus my glides should be longer since there is a lot less wind resistance. The only problem I see is possibly getting stuck at 1 or 2 lights. I can shut off my car then but scangauge still reads fuel usage.

I'll report back here tomorrow and let everyone know how much better or worse it is.

xcel · #2 02-03-2008, 09:13 PM

Hi Bomber991:

___Frontage roads with slower speed P&G’s are the bomb! Literally

___Good Luck

___Wayne

koreberg · #3 02-03-2008, 10:36 PM

If you lower you pulses from 60-45 down to 50 to 40 I would bet you could do even better.

bomber991 · #4 02-04-2008, 06:04 PM

Yeah, so it's completely not worth it. I get stuck at every single light, and traffic is still pretty heavy. Makes no sense to leave 15 minutes earlier than normal for a 20 minute trip. I don't think my numbers were too high cause there wasn't much coasting either. I couldn't really tell though cause the sg still counts fuel usage at all the lights even with the car off, but it said I was at 25.7mpg.

brick · #5 02-04-2008, 06:34 PM

Hey, at least you tried. I've tried dozens of routes and sometimes you get a few flops before you get a good one. I like to break out google maps and piece together the most direct surface-roads path as a starting point and systematically find work-arounds for the really bad bits. The winner is the path that results in the smallest total fuel burned, which isn't always the highest FE. (Depends on the relative distances.)

RichXKU · #6 02-04-2008, 06:46 PM

Stick with it! I was able to get a 29 MPG tank out of the STi this past summer before I even knew what I was doing.

The year before I managed a 26.x tank on a huge highway trip in 95° weather with AC on. (Pre hypermiling days).

I still haven't figured out how to get the most out of the STi, the usual techniques never seemed to work the way I expected.

diamondlarry · #7 02-04-2008, 07:12 PM

I have had a little experience on frontage roads. There is one in particular between Wadsworth, IL and Oak Creek, WI...

shifty35 · #8 02-04-2008, 08:56 PM

I'd venture that a flat 55 mph steady state cruise will yield way better results on the highway than a 70-55 P&G routine. Much less work with a slightly lower average speed...

Assume average speed with P&G is (70+55)/2 = 62.5 (probably lower due to faster speed reduction at high speed)

10 miles at 62.5 mph = .16 hour = 9 min 36 seconds

10 miles at 55 mph = .181818... hour = 10 min 55 seconds

1 minute 20 seconds saved with the P&G routine. I'd guess you're taking 5-6 mpg off your potential by doing it also.

I'll leave the rest of the math (fuel savings) to you to find out if it's worth it.

High speed P&G just isn't what most would hope for, as the aero makes you throw a lot away. Now if you have some nice hills, as I do on my commute, DWL up and FAS down while keeping average speed close to 55 is the winner all day long. Easy 100mpg+ in an Insight...

Right Lane Cruiser · #9 02-04-2008, 09:29 PM

Ben, what you are saying definitely works in the Insight...

HOWEVER...

For my Elantra steady state cruising at 55mph on flat land nets me about 42mpg. When I drove it to Milwaukee over some VERY hilly terrain with BIG hills I used a high speed P&G routine with NICE-ON for the glides (purely because of ECU reboot times throwing the SG way off at the high rates of slowdown at those velocities) with an average speed of 67mph

I know that is really high but I did want to get there in a reasonable length of time... The result was 51.3mpg -- over 366mi or so. I duplicated this on my drive back and kept the tank at that level.

If you keep an eye on the trip mpg and push for improvement on every single cycle of P&G, you can pull better numbers than steady state. You have to be ultra dedicated to do it, though...

desdemona · #10 02-04-2008, 10:19 PM

IF the lights can be timed, you could do better. If the lights can't be timed you will do worse. Learning about the lights can take some time. I think it took me a good month or two to learn how to time the lights on my current commute. I do pretty well and going to work it is not at all uncommon for me to miss every single light (or at least stop at only 1-2 out of 15). There are a couple extra the other way and I can never do it, but I still only stop average of 3 times. Timing the lights is the key. If they aren't timeable, and this is possible then you will make worse mileage, even if you turn the gas off at the lights. Turnign the car on and off, and the rev up will steal your mileage.

--desx