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I thought around town "mpg" was supposed be better.

I noticed a long while back that when I am cruising on the highway, going about 75 mph, I easily get an average wh/mi of well under 300,usually in the 270 range. However around town the avg is much higher which I find confusing because you would think that with all the decelerating, the avg would be much less.

For example, yesterday I drove a total of 32 miles, all of which was in town driving, never getting about 45 mph. I used up 11.3 Kwh to go those 32 miles and had an avg. wh/mi of 353. Granted the A/C was running for the miles driven in the afternoon. I have the temp set for 70 and it was 82-85 yesterday.

Is there something I am missing here?

I have the same experience.

If you do a lot of stop and go driving, the efficiency suffers.

There is a significant energy cost to cooling and heating in the first few miles.

I get around 280 on the hwy and 310 around town in my P85+. The biggest factor around town is how aggressively you accelerate and how regularly you brake vs. letting the regenerative breaking do its thing. Than can easily be a 50 wh/mi difference.

The more time spent stopped while using energy (stop lights, traffic) the higher your average will be. Think about it, you're using energy and going zero miles, how can that not affect your average?

Regen isn't 100% efficient or even close to it. I read somewhere that it gives you about 60% back. No idea how accurate that number is, but the point is that although regen is far superior to no regen, it only partially makes up for stop-n-go traffic.

Acceleration is going to kill efficiency. If my math is correct, accelerating from 0-35 mph uses (roughly) the same energy as driving 1/2 mile at 35 mph. If you do 0-35 in 6s, you'd travel 46m. So per unit distance, accelerating to 35 takes 20 times as much energy compared to driving at constant speed.

I'm expecting this. It's similar to my former XJ-S which was a very heavy car and got truly sucky mileage in town but could get up to 24 on the highway. It's the start/stop that kills efficiency because you have to get all of that mass moving each time. An object at rest tends to remain at rest and an object in motion tends to remain in motion.

Owning two Prii taught me to be a better driver by gauging the traffic, looking farther ahead, learning to sync with the lights, etc. I get 57 winter and 52 summer (high AC load) as a result. I also found that good, economical driving habits are also good, safe driving habits. I'm just more aware of what's going on.

Teach yourself to coast. ICE cars teach us to operate a car like a kiddie pedal car with one foot or the other cranked to the floor at all times. A hybrid or EV wants to be driven differently but it takes better concentration in order to do it.

My habits were so apparent that on my MS test drive the cool Tesla Dude even remarked, "You must drive a hybrid".

It's the physics of starting and stopping a 4600lb car over and over again. On the highway, one you get rolling there is less energy consumed as the cars weight helps to propel it, in the city you lose that efficiency as you have to keep Accelerating the car.

As others have said, a higher wh/mi makes sense if you are stopped a lot during city driving, either at lights or on the highway. When driving on suburban roads and highways at 10-50 mph with minimal braking during rush hour, I use about 40 wh/mi less than steady highway cruising.

The main things that hurt efficiency are speed changes (acceleration), elevation changes, heating/cooling, and wind resistance.

Drive a straight flat smooth country road during the day in good weather with windows closed and hvac off at 30mph with no wind, and you will go a very long distance. Add a 60mph tailwind and you can go forever.

I don't understand the question. Other than hybrids, every car in the history of the world gets better mileage on the highway than in town. Stop and go.

Stopping is the enemy of efficiency. Every time you stop, you basically throw away your momentum. This stop and go will rob you of efficiency. If you can time your city drives to hit only green lights, your efficiency will increase. If you see a red light a few blocks away, start coasting and slowing down gradually so that by the time you get to the light it turns green. While annoying the drivers behind you, you would have preserved as much momentum as possible and would have continued through the light without stopping.

Check out some hypermiling techniques, applying them to your city driving will help you improve your efficiency.

It's a pretty reasonable question. Stop and go doesn't necessarily consume more energy than driving at a constant speed.

IF

1. Energy recovery during deceleration was 100% efficient (it's not);

2. One could totally avoid brake use in town (one can't, even though one can minimize it);

and

3. One could avoid being stationary in order to avoid energy consumption while adding no distance (also not possible)

Then one could achieve better gas mileage in town at an average of 30 mph than on the freeway at say, 55 mph.

Of course, 1, 2 and 3 aren't true, so there is a cutoff highway speed below which one can get better energy usage on the highway than in town.

You can maximize efficiency or fun. Sounds like you've been leading toward the latter :)

Who can blame you?

Leaning, that is

I'm amazed you get under 300 on highway. I usually get 340ish going 75-80 on a fairly flat part of Texas.

Even at the the highest possible Wh/mi rates it is 20 times better than my ICE so I don't worry about it much.

I've notice I can get below 300 when in a clump of traffic even if I'm not specifically drafting (I stay at least 2 seconds back). If I'm on the same road by myself it will be around 340.

@J.T. Unlike ICE the motor does not use any energy when stopped though. Accessories, other than perhaps heater, do not use any significant amount of energy.

I too can't get even close to 300 at highway cruising speed, 75~80 in my case.

EVs are just like ICE cars in terms of mileage. city worse than hwy.

Hybrids "seem" to have higher MPG in city versus highway versus basic ICE cars but the issue is they get poor mpg until their engines warm up. They use a hot engine efficiently when rolling (momentum) and use the battery for the stop-light acceleration to not draw as much gas during the "go" part of stop-and-go.

I've had a P85+ since 3/24 and I'm amazed that @jordanrichard got a range of 270 mi traveling at 75 mph. I drove from Los Angeles to Napa on Highway 5. Starting with a fully charged battery, I had to recharge twice. The trip was approximately 450 miles. The range from my first recharge in Coalinga, CA to where I had a remaining rated range of 5 miles in Livermore, CA was approximately 150 miles. The range from my full second recharge in Fremont, CA to Napa, CA was approximately 75 miles with a remaining rated range of 90 miles. My average speed from the first recharge to second recharge was approximately 80 mph. It was windy and was a lot of the terrain was uphill.

My daily driving is almost exclusively on city streets (no freeways/highways). The rated range when fully charged is 265 miles. Most daily trips average 5 to 20 miles. I average 165 miles per charge.

Iowa2x, the reason for the question is because hybrids run in pure electric tooling around town, until the battery runs low. Since on the highway hybrids run off their engines, their highway mileage is worse than city.

So I presumed the city "mileage" would be better for the MS since there are far more times/opportunities for regen. I guess it's due to not having enough cruising time to lower the energy average from the acceleration.

There is a tendency for people to think that EVs are more efficient at stop-and-go than they are on the highway. I think the reason for this is that people keep saying "EVs are so much more efficient in the cities" but then what they are actually comparing it to is ICEs. I.e., "EVs are so much more efficient than ICEs are in city traffic" not "EVs are so much more efficient in city traffic than they are on the highway". In the public mind those two meanings get confused and so you get the misconception forming.

I've found it can be very efficient getting in traffic on the freeway (albeit no less boring). When doing gradual starts/stops in the 10-30mph range I get low Wh/mi usage, it's all gentle accel and regen. Around town if I drive like a granny I can get rated range or better even with stoplight-to-stoplight stuff, but usually if I'm driving around town it means I'm close to home and I don't really care. The cost to recharge the extra 10 miles worth of range or whatever is negligible.

Sounds good compared to my Volt. I used all my battery (9.7 KWH) going 32 miles @ 65 mph with temps in mid 80s a few weeks ago. Tesla a heavier car. Startup from a stop uses lots of juice.

From a Tesla wannabe owner.

@cquail: I have never gotten that low a mileage in my Volt other than in 30*F weather outside and using some seat heaters. Did you have full-blast A.C. going? I got about 44 miles today in my Volt - a 2011 model using whatever it has for state of charge. One tip to getting more mileage in a Volt or any EV is to finish your charging just prior to leaving. Don't use full blast climate control. And keep your tires at 40-41 psi.

The comments about accel etc. above are right; all those things work against you in city traffic, and the EPA ratings reflect this, showing ~87MPGe city and ~92MPGe highway. I was surprised on first reading this, because electrics get better mileage at slow speed. That works for you, as does regen. But the frequent changes in speed are a stronger influence.

If you could drive steadily through the city, at say 30mph, catching every light, etc., you'd do better than when driving 80mph on the highway. Fat chance, though!

Constant low speed (best around 40km/h or 25mph) is more efficient. This is more common in the city streets than highways. But you also have deceleration (not 100% efficient) and braking (all loss)... And acceleration has its own non-100% efficiency. There are, thus, many factors at play.

During the day my city driving is comparable to my highway driving. When traffic reduces and I relax (nowhere to rush) my city consumption is way better than highway - so good I could switch to use "ideal range" display.

The speed limits where I do most of my local driving, are between 35 and 45. Real world that means traveling between 40-50 mph. I guess the issue is that you can't go more than a half to 3/4 of a mile before hitting another traffic light.

I get better mileage in town than on the freeway. Freeway at 75-80 I get about 345. This improves a lot with non stop and go traffic. In town going 25-30 without too many stops I can get 515 to near 300.

Assuming you're not heating or cooling, energy usage during idling is so minuscule that it's not even worth mentioning. Heck, I'll throw in climate control and I bet you the energy "wasted" while idling is not as high as you think

The following is guesswork, but let's very very generously assume

LCDs ~ 50W
Onboard computer systems ~ 200W
Sound cranked ~ 250W
Headlights ~ 20W
Heater full blast ~ 2000W
Misc stuff - 50W

That's 2570W (or 2570Whr per hr)
Which equals 43Whr/min. That's how much energy the accessories are using, thus how much energy is being 'wasted' while idling, assuming the powertrain doesn't use ANY energy while stopped. A minute of idling is equal to 9 seconds of forward momentum (310wh/min = 5.17wh/sec. 5.17 * 9 sec = ~43W)

So let's say you're idling 25% of the time, 15 minutes on the hour. That means after an hour you will have wasted 645W while idling after an hour of driving. That's about 2 minutes worth of forward momentum. That's like a mile in the city?

Get rid of the climate control and drop idling to 10 minutes per hour and you will have 9.5wh/min with wasted energy while idling being about 18 seconds of forward momentum.

And again, I am being very generous with the numbers, unless I made some error somewhere (which is very much possible). But I bet the 17" LCD doesn't even hit 20W, with normal people the heater isn't full-blast but a few minutes until the cabin gets warm. I didn't take into account the energy used for some of the automotive stuff because I honestly don't know how much energy it takes, but I assume it's not much for not long (brakes being applied, suspension raising, etc.)

Don't underestimate how much energy it takes to move a 2 ton vehicle through wind at great speeds. It takes the lion's share of energy every day of the week.

I think the reason it costs more energy around the city is because the regen isn't as efficient as everyone makes it out to be. You're not going to recover the energy spent in drag, rolling resistance, powertrain inefficiency (x2), and the AC-DC/DC-AC inefficiency. But it still beats the hell out of 100% of it going to friction.

Highway w/o regen (coasting) is better than
Highway w/ regen is better than
city w/ regen which is better than
city w/o regen


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