Two Possible Commute Routes - Which one to use?
 

I have a 28 mile commute. The first leg of the drive is getting to the freeway. There are two plausible ways to do this:

Hilly but short
4.1 miles, 9 minutes (based on Google). I have five spots on this route where I need to either stop or slow down at the bottom of hills. GRRR! The biggest hill is over 200' of elevation change in half a mile. I climb it in the morning and engine brake down it in the afternoon (2nd gear). Stop sign at the bottom.

Longer, but flat
7.2 miles, 15 minutes, three stop signs, quite flat.

My goal is lowest fuel consumption, not necessarily best mpg (the second route would obviously be better for that). What do you all think?

I'd go for the longer but fewer (and less painful) stops. Those bottom-of-the-hill stops are absolute mpg killers, especially with an automatic.

If you have a gauge, try both ways a few times and the results will show you for sure which is better.

The longer route is 75% longer.
There'd need to be a VERY large difference between the fuel consumption on both routes to make up for those 75%.

Take the short route a few times and fill up.
Take the long route as often and fill up again.
Compare.

My vote is on the short route.

Here are the two routes. I'm happy to see that the answer is not obvious! ;)

http://goo.gl/maps/Cha8

Thanks for the feedback so far.

Take the short cut to work and take the long way home...

I got to thinking more about it arcosine and I think you are right. If I climb that hill in the morning, I can convert most of that potential energy back into kinetic with minimal braking along the rest of the route. On the way home, I'm engine braking and disc braking all the way down that hill to the stop sign.

Peaking the hills at :turtle: speed is key to not braking at the bottom - hopefully not too many people will get angry at me for taking part of the route at a slower pace. :)

Climbing the hill will allow me to spend time at my best BSFC too based on what I can find on the topic. Anybody have a chart for the 2002 GM 3800 engine?

Probably similar to the Saturn engine posted here.

http://ecomodder.com/forum/showthrea...-got-1466.html

http://forum.ecomodder.com/attachmen...9&d=1205914740

But hven't you slipped into what you said you did NOT want to do - chose efficiency over absolute fuel use? If you get 25 mpg on the short hilly route you would have to get 44 mpg on the 75% longer flat route to break even. I really doubt the difference in mpg between the two routes is going to be anywhere near that large.

You may be right, and that's exactly what I'm trying to determine. My overall FE is only 24. I'm guessing that on that hilly route home, where I brake on every downslope, coming to a complete stop at the bottom of the largest hill, my FE is 12-15. In that case, 25-30 on the longer route would be a winner; since it's a gentle drop in elevation along that route; I think it's plausible.

I may just have to spend some coin on the SGII. I do have some Christmas money left.... :p

Keep in mind you can also get an Ultraguage for about $70 before rebate. And I agree that minimal fuel usage >> higher mpg.