As I live in the hilly S.F. Bay Area, I inevitably have to occasionally drive up rather steep hills. It seems that FE always drops sharply, no matter how fast or slow I accelerate. What is the best way to increase fuel economy while driving uphill? Thanks, everyone.

 

there is no escaping the physcis but method i have found , when safe is to get good runnin start before entering the hill , enough not ot labor going up

 

Yes, I tend to think it best to hit a pulse up a few MPH on either the flat or downhill (best) before the hill and then use a light foot up the hill and allow the speed to fall while trying to hold MPG as high as possible.

It depends on the hill, though. Very steep hills are just bad and I try to avoid them via alternate route. I don't have any mountains here in Charleston, so I almost always have a down hill on the other side.

So, I try to 'get it back' going down the hill by gliding...

 

Ditto that. There's no beating gravity. Keep a constant throttle and try to judge that you will make it up without slowing too much. Remember, you are not the only car on the road, and don't make yourself a rolling roadblock like some here might suggest.

The worst thing you can do is try to accelerate uphill. I always cringe when I see someone doing that.

 

Get sufficient momentum and try to stay in your power band as long as possible.

 

boplives, give us a little more detail about the hills and where you are at. Are they super steep (like Hyde for example) with city traffic, or are they more rolly, suburban hills? When you start out in the morning, do you go up or down? How about coming home? How many miles is your commute? Also, how do you handle the downhills?

As others have said on this thread, try to do your acceleration on the flats and downhills and keep your engine load even on the climbs. Focus on bringing your iFCD down to the 30mpg range at the very bottom of the hill and keep it there all the way to the top, even if you lose some speed.

If you find that you are losing too much speed and that you need to add gas in the middle of the hill (dropping below 30mpg), then your start point was too high. Next time, try the same hill at ~25mpg, then ~20mpg then whatever until you find the load you need to get to the top of the hill at your miniumum safe speed.

Of course, all of this goes out the window if you hit a red light on the climb. If you see that you are going to need to stop, let off the gas enough so that you come to a stop in the right place without touching your brakes until the last few feet. Edit: there are two schools of thought regarding acceleration on hills--using assist and avoiding assist. If my battery is pretty full, I will let the car use as much assist as it wants to since I know I will pick it back up on the other side. Others feel that you are using too much gas when assist comes on and you should minimize this as much as possible. Here a little experimentation is key to figure out what works for you.

As I stressed in my first paragraph, the downhills are just as important as the climbs. If you can, only use gas when you are at the bottom 1/3 of the hill and getting ready to hit your next uphill. Other than that last 1/3, you should be in a glide. If you are going too fast, let your brakes or regen slow you down, but keep the valves closed. If you are starting out on a downhill from a stop (and on a multi lane road), accelerate to 15-20mph and then let gravity do the rest of the work.

I get my best mileage in the hills and the mountains. If I have a choice between a gradual uphill for 100% of the drive or a steeper uphill for 70% and a downhill for 30%, I will take the second choice--the gas free coasting down more than makes up for the extra work in my experience.

That being said, we don't have many super-steep downtown San Fran style hills so you'll need to play around there and see what works for you. If you aren't already resetting your Trip B every time you drive, that is a MUST if you want to improve in the hills. Keep a mental note about what your FE usually is at specific points and that way you can see if something you try yields better or worse results.

Good luck!

 

The one very steep hill is the one which goes to my (detached) garage. It is only about 200 feet but is narrow and I can only go about 5 or 10 miles per hour. The others which I was wondering about are more gentle, such as freeway on-ramps, where it seems very difficult to get up any kind of speed without going up to about 3000 rpm. At any rate, thank you for the detailed response. I'll give your method a try.

 

On your last uphill to the garage, it might be worth trying "S" to get up if you are getting there with a low SoC (there was a discussion on this that I think you posted to). If your SoC is 6 or above though, I think using "D" and letting the juice flow would be good. Unfortunately, it's going to be tough to compare the difference in mpg for such a short section (I'm guessing).

Another thing I didn't mention in my original post is to pay attention to the traffic lights. If you are on a downhill and approaching what you know will be a red light, apply gentle brake pressure earlier than you would in a normal car. Alternatively, you can also use "S" to get the same effect if you don't want to appear to be riding your brakes. A longer, slower stop will allow you to store more electricity which will come in handy at some point on the next hill. If you use "S" just don't forget to shift out of it before your next traffic light or you won't get autostop.