Why would highway mpg be lower than city mpg in a hybrid?

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Old 11-30-11, 08:02 PM
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Why would highway mpg be lower than city mpg in a hybrid?

I swear I saw this on a webpage and I'm having trouble accepting it. The webpage said that for a Camry hybrid the highway mpg was lower than the city mpg. Not by much - only 3 mpg - but the opposite of what I would have expected. Am I reading this correctly? If so, why would this be the case?
 
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Old 11-30-11, 10:26 PM
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In the city the car runs mainly on the battery. When the engine kicks in, it is only for a short time and it shuts off every time you stop for a traffic light. On the road, you are traveling at a higher speed and without many stops, so the engine is running most if not all of the time. Hence lower mpg on the highway.
 
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Old 12-01-11, 06:39 AM
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I have seen that with several cars and I think they all are hybrids. After seeing highway mileage higher all my life it is odd to see city mileage higher.
 
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Old 12-01-11, 06:51 AM
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It's not all that odd, small trucks from yesteryear were like that. I have a 51 Ford F1 that gets it's best fuel mileage around 45 mph. It uses more gas at 60 mph than it does at 30..... but it's geared low and would struggle to go faster than 70 mph.
 
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Old 12-01-11, 10:37 AM
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A hybrid on the freeway is nothing more than a car with a slightly smaller gas engine than its non-hybrid counterparts. As stated, that gas engine is not in use all of the time in city driving.
 
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Old 12-29-11, 09:04 PM
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Hybrid MPG

I have a 2005 Prius that I bought new and have driven over 92,000 miles. I get the best mileage ON THE HIGHWAY. That's correct. City driving does allow the engine to stop while at red lights and in traffic backups, but that's only good until the battery runs low enough to cause the engine to run to recharge it. Also you get single digit MPG every time you accelerate off of dead stop unless you accelerate v-e-r-y s-l-o-w-l-y. That can cause a lot of angst among drivers behind you so it's not always smart to do..

Be advised however that my highway driving is probably slower than most people. I drive at or up to 5 mph below he speed limit most of the time. Sometimes slightly above but that's the exception. The 2005 Prius rides on 185r15 tires so high speeds are not achieved smoothly. The car will do 100+ mph - don't ask me how I know- but like every car has its optimum speed, mine has it's smoothest most vibration free operation below 65 mph. I can achieve 52+ mpg on the highway, but rarely get over 49 mpg in steady city stop and go driving. Also, outside temperature affects mpg as cold weather causes the engine to run frequently to maintain catalytic converter operating temperature and keep the passenger cabin warm (unless you like driving cold)..

So if you are an impatient and aggressive lead foot like so many drivers are these days, you won't see great mpg in a hybrid. But if you learn how to drive moderately, feather the gas pedal and use gravity to maintain momentum or coast at every opportunity, you can achieve high mpg on the highway.
 
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Old 12-30-11, 06:30 AM
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if you learn how to drive moderately, feather the gas pedal and use gravity to maintain momentum or coast at every opportunity, you can achieve high mpg on the highway.
That's true no matter what kind of vehicle you drive
 
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Old 12-30-11, 08:40 AM
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I used to drive as fast as I thought I could get away with (radar detector included) but when gas spiked several years ago and my wife and I were spending $600/month in gas (driving about 60 K miles per year between us), I dropped to one or two mph over the speed limit and I saw my milage increase about 10%.
 
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Old 12-30-11, 01:08 PM
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My new car has an instant mileage display. It's interesting to note how much the mileage falls off at faster speeds on the highway. I definitely do not set a mileage record with the cruise control set on 80. Even though it's highway driving pushing the air out of the way at higher speeds takes a lot of power.
 
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Old 12-31-11, 05:12 AM
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My 2010 jeep has the same thing but I think it's more propaganda than anything else. It consistently shows me getting 1-2 mpg more than what I actually get
 
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Old 01-18-12, 04:53 AM
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Because on the highway you are cruising in a higher gear. And in the city you are stopping and going in traffic.
 
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Old 01-28-12, 08:13 AM
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Prius does not have gears. Has PSD - power sharing device - which is also called CVT - continuously variable transmission - but is, in a nutshell, a planetary gear mechanism with 2 motor generators connected to it.
his Prius is very unusual in this respect. any speeds above 70mph kill mileage on Toyota HSD systems. They work the best at about 55mph. Continuous or prolonged city driving kills mpg also, as battery lasts only about 20 minutes in HWY stop n go traffic, and less than that in city cycle.
Overall, best mpg is accomplished at around 40-45 mph long straight roads.
reason it does worse on HWY is because ICE - internal combustion engine - works all the time. It turns on after 42mph, to prevent MG2 from burn out. Hence, at HWY speeds, it's simply a regular car with petrol engine. After that, it's question of air drag and how good driving habits are.
Graham's Toyota Prius

PS my TCH - Toyota Camry Hybrid - will go 125. don't ask. I think, I did not max her out either.
 
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