Hill Climbing
 

I have the wonderful benefit of coasting downhill for almost the entire 5 miles to work at 60+mph, however I have some options on the return trip that I wondered if you'd have some insight.

1.) The same road in reverse is a steady 2.2% uphill grade on a 65mph interstate.
2.) A backroad provides flat driving up to the hill and then an 8.5% incline for a shorter distance. Even with the speed limit at 45mph, I can't maintain 30mph if I hold the RPM under 2000. I need 2400 RPM to stay steady.

I don't have the blessed SG yet, so I'm wondering what you would do? My car is a 99 Camry LE 4cyl. Any suggestions?

Could you give the mileage of each section? The distance of the 2.2% grade and the distance of the flat and 8.5% grades? What is the weight of your car (as this comes in to play on hills)

Option (1) 300 ft rise over the 2.6 mile run - with about 1 mile flat
Option (2) 220 ft rise over a 0.5 mile run - with about 3 miles relatively flat

Details aren't exact but should give you an idea of the route.

I have no idea what a 99 Camry would weigh - maybe 2500 lbs?

For going home, if you can pulse and glide on the backroad until you hit the hill then I would think the backroad is better. Go up the hill at 50%+ throttle and P&G some more home. I don't think P&G would be practical on a steady uphill on the interstate for you.

However if you are not opposed to drafting, stay 2 seconds behind a transport on the interstate and you'll probably beat your MPG on the back road plus get home faster. I had the fortune of getting a draft all the way home from work yesterday and got 53.5 MPG out of my neon, typically I get 36 MPG on the same route doing some P&G.

Once you get your scangauge, you'll answer your question in two trips home and you'll see how far back that drafting works!
Ian

Just a guess, as a lot depends on the particular car & such, but I'd say you'd be better off going for the back road. Speed up as much as you safely can before starting the steep section, and try to let momentum carry you up without needing to downshift.

I drive an Insight, and find that on some hilly sections drive often, I can get better mpg by driving fast enough to keep RPM/power up in 5th, rather than going slower and having to downshift to 3rd. Your car & road may vary, though.

I find the same thing, getting caught on a hill that my car can't climb with torque converter locked in top gear is a bad MPG situation. Its worth the slightly worse MPG speeding up for the hill to be able to motor up it easily.
This also limits my minimum speed for pulse and glide to about 35-40 mph, any lower and I downshift on my pulse wasting gas.
Ian

The 1997-2001 Toyota Camrys weigh roughly 3,100 pounds. :)

I would do each commute for 3 days (refueling at the end of the 3 day period) and then switch. If the route home is the biggest variable in the usage of the car by switching back and forth a few times and recording the mileage you will find that one is a clear winner in MPG or you will find that the results are inconclusive which means take which ever one you want.