Route conundrum...

[christofoo]

On my SGII / Civic I typically get about 55 MPG in the summer regardless of the route (<65mph intra-city routes that is) so I always choose a shorter route to get lowest number of gallons per trip.

BUT this is a skill I've honed with the SGII and I'm doing advanced hypermiling, DWB and extensive EOC, in a manual tranny. Without those techniques it's possible for a shorter city route to yield higher total gallons, although even being minimalistic, DWB and engine-off at lights, mpg shouldn't be too different between city and highway. Neutral-gliding or P&G on downhill also neutralizes the effect of the hill, even without EOC.

Hills and lights are mostly non-issues for me unless there is some loss that can't be avoided, i.e. downgrade too steep or a stoplight at the bottom of a hill or a downhill freeway off-ramp, requiring brakes or engine braking, etc. Even then it sometimes just averages out.

Eco-driving can be done wrong though. Owning a gauge is money.

[GRU]

There is a formula...how long is your route? you need to figure out the percentage...if the longer route is 5% longer and you can get 5% better fuel economy then you are breaking even...but if it's 5% longer and you get 10% better fuel economy then you're saving fuel.

I know you don't have instant feedback so it's hard for you to figure out what fuel economy you are getting on the different routes but i can almost guarantee it's always cheaper to go the shorter route

[razor02097]

It's 27% longer. My daily commute isn't that far. It is 64% highway and 36% city.

[slowmover]

but i can almost guarantee it's always cheaper to go the shorter route

The number of full stops is the killer. Not so much a penalty on the gasoline go-karts as compared to diesel trucks of any size, but it is still there. Wear & tear is cumulative over tens of thousands of miles. That is still the metric about saving money.

The heavy subsidization of fuel in this country makes chasing a few tiny tenths nearly meaningless. It's the cost of the vehicle over X-miles and Y-years that is the starting point. Extending the life of a vehicle over several more years is where true savings are found. Fuel cost is just one of a couple of variables under control of the driver. The rest is a fixed game.

.

[christofoo]

Originally Posted by slowmover

but i can almost guarantee it's always cheaper to go the shorter route

The number of full stops is the killer. Not so much a penalty on the gasoline go-karts as compared to diesel trucks of any size, but it is still there. Wear & tear is cumulative over tens of thousands of miles. That is still the metric about saving money.

The heavy subsidization of fuel in this country makes chasing a few tiny tenths nearly meaningless. It's the cost of the vehicle over X-miles and Y-years that is the starting point. Extending the life of a vehicle over several more years is where true savings are found. Fuel cost is just one of a couple of variables under control of the driver. The rest is a fixed game.

.

I've put a lot of thought into this and I disagree on the economic bit. At least - in the context of the cars that I drive.

My Corolla in the 220k neighborhood:
$0.08 per mile repairs + maintenance over the last 33k
45MPG @ $3.6/gallon = $0.08 per mile (28MPG = $0.13/mile)

(I'm pretty sure the wife's Civic now in the 150k neighborhood has been significantly lower than that in repair $ per mile for the last 50k, but I haven't actually tracked it.)

(Razor never said it was about money. For all we know he wants to minimize CO2.)

[razor02097]

Originally Posted by christofoo

(Razor never said it was about money. For all we know he wants to minimize CO2.)

Post #7 sorry...

Don't get me wrong though all of the emissions equipment has remained operational on this vehicle. I maintain and repair any that fault. So I am obeying federal law and doing my part to keep the EPA happy.

[larrybuck]

Another aspect to consider is the accident potential of each route. If you are trying to coast up carefully to keep an even speed, and avoid a full stop at any of the lights,
someone less patient will invariably have some kind of conflict with you.

Pennies difference will mean little if your car gets hit, or if you are constantly being
flamed by other drivers.
I think it is easy for you to see I vote for the longer road with peace of mind!

[razor02097]

Well after 3 tanks the vacuum gauge has net me an extra 1.5MPG average. I went ahead and ordered a MPGuino from JellyBeanDriver. I have the ability to datalog right now but there isn't any real time easy numbers I can look at for efficiency other than the injector pulse width.

Something else I did was to install a brake light button for 2 reasons... 1 people here get right on your ass and don't pass you. I can hit that button a few times to act like I'm slowing down so they get in the left or center lane. The other reason is engine braking. People in their automatics don't know what that means and plow in to the back of you. When I exit the freeway I can engage DFCO and push that brake light button.

Here it is...


When the brake lever is down I just rest my hand on the hand brake and push the button.

[XYZ]

What is your typical speed on the short route, excepting having to stop for lights or slow for traffic?

The trick is to stay in a relatively high gear for as long as possible. If you are at near highway speeds (above 40 MPH) for most of the short route, that is the most economical option - even though the long route may be less stressful driving.

[razor02097]

The short route is 2.1 miles. Average speed over the short route in a 15 day spreadsheet record is 19.6MPH @ 6 minutes 25 seconds. This was calculated by taking the average of the speeds and times over the 15 day period. This route includes 5 stop lights that are poorly timed, a small ascending grade and a large hill. I can time the lights but it takes a lot of throttle which is inefficient.

The long route is 5.7 miles. The average speed over the long route is 41.6MPH @ 8 minutes 13 seconds. I only have 3 data points so far (3 days). This route has only 1 stop light. There is a small descending grade initially then it flattens out the rest of the way.


I can keep a much higher average speed here but it takes about 2 minutes longer and I have to travel 3.6 miles further. It might not sound like a lot but it is more than two and a half times the distance of the short route.