DWL hasn't worked well for me. Luckily I'm in a mostly flat area with a lot of farms.
What I generaly do is if coming up on a hill with a low grade I'll hold my speed and while on the flat at 40 mph I'll usually get 58 - 60 mpg if I hold 40 on the slight upgrade hill it will usually drop to 38 - 42 mpg depending on grade.
Now with steeper hills I'll hold 40 mph as long as possible and my mpg will slowly start to drop and then at around 36 mpg it will take a sharp drop to around 24 mpg and keep dropping depending on the steepness of the hill.
As soon as it drops off mpg wise I'll downshift and floor it up the hill. Generally the difference of holding 40 mph and accelerating is 22 mpg vs 18 mpg except when I get most of the way up the hill while flooring it I'll have gained 10 - 15 mph at which point I try to time a neutral coast so that I am back at 40 mph when I hit the plateau as I've noted better fuel efficiency doing that versus flooring it all the way to the plateau and then doing a neutral coast or bogging down and having the mpg fall into the teens trying to maintain speed.
My car doesn't seem to do slow accelerations very well. If I'm doing 40 mph and getting 60 mpg and want to get to 50 mph and accelerate slowly, during acceleration my mpg will drop down to the mid to high 30's and then when I get to 50 mph my mpgs will raise to around 52.
Instead I employ a more rapid acceleration keeping my rpms between 1,200 - 2,200 for when changing speeds on the flat or accelerating from a light.
I even went to far as to take a parking space at work that is farther away but is a pull through space on a downhill so I glide into the space on EOC and when leaving I just drop the emergency brake and get the car up to about
10 - 12 mph before I even have to start the engine.
I also got a new garage door remote that has a farther range so I can open my garage door while driving past my neighbors house and EOC all the way up the driveway and into my spot instead with my old remote pulling into the driveway 10 ft away from the garage door, clicking it to open and then waiting a good 30 seconds for it to open and then pull in.
Little things like parking in the garage and then walking to get the mail instead of pulling up to the mailbox, idling for 20 seconds, then accelerating from a stop has added a good 1 or 2 mpg per tank.
I also think I'm very lucky to have a route in which a good portion of it is 2 lanes per side and not very busy and the rest is one lane per side with plenty of passing opportunities so it's not that big of a deal for someone to get around.
My wife thinks I'm a dork and hates to hear about ecomodding/hypermiling.
Though some of it started to rub off when I told her I saved $800 in gas over the past 14 months compared to EPA estimates.
She is getting a good 32 - 36 mpg out of her '05 V6 Malibu though she won't let me make a profile for her.
