Need help with mileage, Please!!!
#11
06-12-2007, 08:27 AM
Re: Need help with mileage, Please!!!
I'm going to hit my one-year anniversary this weekend. I won't claim to be an expert with any hypermiler strategies or anything, but just from analyzing my own driving, etc vs mileage, I've managed a decent understanding of what it takes to get ~40 mpg when it's not super-cold out.
Some of my main insights have been:
- Cruise control on the highway. I saw very quickly how a negligible change in pressure on the accelerator, with no noticable speed change, could cause a significant shift in mpg so I decided the cruise control computer was probably much better able to figure out the minimum fuel needed to keep me going at speed. I tried various things like coasting up toward the tops of hills to stop using extra fuel on the incline, but the additional fuel needed to recover speed after.. maybe there's a benefit in there somewhere but I decided it wasn't helping me so I just stick to cruise. Brake when I need to slow down for traffic, resume when I can, use the CC **** to adjust speed rather than doing it myself....
- Coasting. Especially getting off the interstate. Most of my highway exits are coming off hills as well, so I just turn off my cruise control (or tap the brakes if I'm just going through an interchange) at some point that I've learned is a pretty good point for coasting down to where I can hit 40 on the ramp and have the engine drop out of gas mode. You can get a lot of distance coasting to a ramp, at 60+ mpg. And never forget that any stretch of distance you can manage to do purely on electric, like coasting down the ramp, etc, is a major boost to your mileage. Think about it, if your basic travel economy is 35mpg, for a 20 mi trip, you're using a bit more than 0.57 gallons. If you manage to cruise on battery for just one mile of that 20, you end up using 0.54+ gallons, and over a 20 mile trip that's a jump of almost 2 mpg right there, to just under 37.
- Moderate highway traffic is good, heavy traffic is bad. My experience is that if highway traffic keeps your speed down around 30-40 mph, you get to run on battery a lot, get a big boost to fuel economy, but move enough to keep from running your battery dry. Heavy traffic, I find myself using battery for every slow foot I travel, never getting enough speed to really recharge the battery. And when you run the battery low enough for the gas engine to kick in, suddenly you're burning gas to sit still, which is 0 mpg, very bad.
- Cold is bad. Very cold temperatures dropped my mileage from close to 40 to low 30s during the coldest part of the year. And mathematically, all the extra gas used during those cold weeks is going to take a lot of travel at high fuel economy to get back up near 40 again. My last tank was over 40 (maybe over 41) but my average is still under 36 for the whole year, due to 5 or so cold weather tanks.
- As most of us know, 40+ basically means burning gas, 40- means, if the engine's warm and other conditions met, you're _usually_ able to run on battery. Sometimes at a stop I find I have to semi-abruptly pull my foot off the brake to jerk the car out of gas-burning mode (sometimes off the highway, if I have to brake and accelerate at all it jumps to burning gas and sometimes I can't get it to switch back for a good couple minutes at a full stop, despite full battery and 20 miles to warm up in warm weather--drives me nuts!). But you need to get enough speed sometimes via gas in order to coast/glide and help the battery recharge. You may not be able to get all that far on pure battery before it runs dry and just starts eating gas.
Advice, keep your eye on that fuel economy gauge. Cruise on the highways; figure out what you're doing that makes it drop below 30-40 mpg, and figure out how to reduce that driving behavior; try to make sure you're getting good stretches when you're doing 60 mpg or running on battery, especially if you can get good distances coasting down to ramp speed off highways, etc--but try to accelerate gradually getting _on_ the highway too, maybe shoot for acceleration keeping your fuel economy no lower than 20 mpg? And obviously reduce (if your climate allows) use of AC, etc. Doing errands, they say you should do the furthest ones first because you have more time for the engine to warm up--a lot of short cool trips means bad mileage. If you've been driving on the highway a while, battery full and car warm, try to maximize electric-mode driving, at or below 40. I do this on my way home, keep it from using gas as much as possible for the last part of my commute--or coasting all the way from the highway to my employer (can be a challenge) and riding battery all the way to a parking space. It all adds up.
I'll shut up now, but one year in, a few quirks aside, I still love the car!
Some of my main insights have been:
- Cruise control on the highway. I saw very quickly how a negligible change in pressure on the accelerator, with no noticable speed change, could cause a significant shift in mpg so I decided the cruise control computer was probably much better able to figure out the minimum fuel needed to keep me going at speed. I tried various things like coasting up toward the tops of hills to stop using extra fuel on the incline, but the additional fuel needed to recover speed after.. maybe there's a benefit in there somewhere but I decided it wasn't helping me so I just stick to cruise. Brake when I need to slow down for traffic, resume when I can, use the CC **** to adjust speed rather than doing it myself....
- Coasting. Especially getting off the interstate. Most of my highway exits are coming off hills as well, so I just turn off my cruise control (or tap the brakes if I'm just going through an interchange) at some point that I've learned is a pretty good point for coasting down to where I can hit 40 on the ramp and have the engine drop out of gas mode. You can get a lot of distance coasting to a ramp, at 60+ mpg. And never forget that any stretch of distance you can manage to do purely on electric, like coasting down the ramp, etc, is a major boost to your mileage. Think about it, if your basic travel economy is 35mpg, for a 20 mi trip, you're using a bit more than 0.57 gallons. If you manage to cruise on battery for just one mile of that 20, you end up using 0.54+ gallons, and over a 20 mile trip that's a jump of almost 2 mpg right there, to just under 37.
- Moderate highway traffic is good, heavy traffic is bad. My experience is that if highway traffic keeps your speed down around 30-40 mph, you get to run on battery a lot, get a big boost to fuel economy, but move enough to keep from running your battery dry. Heavy traffic, I find myself using battery for every slow foot I travel, never getting enough speed to really recharge the battery. And when you run the battery low enough for the gas engine to kick in, suddenly you're burning gas to sit still, which is 0 mpg, very bad.
- Cold is bad. Very cold temperatures dropped my mileage from close to 40 to low 30s during the coldest part of the year. And mathematically, all the extra gas used during those cold weeks is going to take a lot of travel at high fuel economy to get back up near 40 again. My last tank was over 40 (maybe over 41) but my average is still under 36 for the whole year, due to 5 or so cold weather tanks.
- As most of us know, 40+ basically means burning gas, 40- means, if the engine's warm and other conditions met, you're _usually_ able to run on battery. Sometimes at a stop I find I have to semi-abruptly pull my foot off the brake to jerk the car out of gas-burning mode (sometimes off the highway, if I have to brake and accelerate at all it jumps to burning gas and sometimes I can't get it to switch back for a good couple minutes at a full stop, despite full battery and 20 miles to warm up in warm weather--drives me nuts!). But you need to get enough speed sometimes via gas in order to coast/glide and help the battery recharge. You may not be able to get all that far on pure battery before it runs dry and just starts eating gas.
Advice, keep your eye on that fuel economy gauge. Cruise on the highways; figure out what you're doing that makes it drop below 30-40 mpg, and figure out how to reduce that driving behavior; try to make sure you're getting good stretches when you're doing 60 mpg or running on battery, especially if you can get good distances coasting down to ramp speed off highways, etc--but try to accelerate gradually getting _on_ the highway too, maybe shoot for acceleration keeping your fuel economy no lower than 20 mpg? And obviously reduce (if your climate allows) use of AC, etc. Doing errands, they say you should do the furthest ones first because you have more time for the engine to warm up--a lot of short cool trips means bad mileage. If you've been driving on the highway a while, battery full and car warm, try to maximize electric-mode driving, at or below 40. I do this on my way home, keep it from using gas as much as possible for the last part of my commute--or coasting all the way from the highway to my employer (can be a challenge) and riding battery all the way to a parking space. It all adds up.
I'll shut up now, but one year in, a few quirks aside, I still love the car!
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