Why is my Gas Mileage So Great?
08-11-13, 07:59 PM
#1
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Why is my Gas Mileage So Great?
I would like to know if there is a reason why my gas mileage seems so much higher than everyone else's. I have a 2000 SC 400, just 48,000 miles, completely bone stock. I average 34 mpg, city/highway combined. Last week, I drove 360 miles and used just 9.88 gallons - that's 36.4 mpg, averaging about 85 mph most of the way (gotta love Arizona highways). I am a pretty aggressive driver, I love the sound of the 1UZ at high revs and I like to push it hard on a regular basis, yet my average mpg is consistently in the 34-36 mpg range. What could be the reason that my gas mileage is so much higher than everyone else is getting? I'm not complaining about it, of course, just curious.
The only thing I can think of is that I live in Arizona, and the 91 octane gas here is about 15% ethanol.
The only thing I can think of is that I live in Arizona, and the 91 octane gas here is about 15% ethanol.
Last edited by supra9398; 08-11-13 at 08:05 PM.
08-11-13, 09:12 PM
#2
are you trolling? at 85 mph even a prius doesnt get 36 mpg. so i'll just assume you're trolling or really bad at math and leave it there.
if you're not trolling, then your odometer is broken, u got some tiny *** wheels/tires or a different rear diff and ur car is racking up miles faster than it should, thus making the gas mileage look better than it is.
if you're not trolling, then your odometer is broken, u got some tiny *** wheels/tires or a different rear diff and ur car is racking up miles faster than it should, thus making the gas mileage look better than it is.
08-12-13, 11:07 AM
#6
The reason you can achieve that is because your 2000 sc400 not only has vvti which the older SC's do not and a much better factory tune (stricter emission standards), your 2000 model is also equipped with a 5 speed automatic transmission and different rear end which only the 400's received (sorry 300 guys) very late in production.
Doesn't seem like a big deal, but all of that translates into being able to achieve much better mileage than everyone at highway speeds because of the much lower final drive on the newer models even though the overdrive is very similar. This would make it a dog in the city though, which is why its paired with an extra gear that is much closer ratio 1-4. This is how the newer SC400's get crazy gas mileage on the highway.
1992-1997? Lexus SC 400 4.0L V8
A340E
Ratios 1st:2.804, 2nd:1.531, 3rd:1, 4th:0.705, Reverse: 2.39300 Final 3.916
1998?-2000 Lexus SC400
A650E
Gear Ratios: 1st 3.357 2nd 2.180 3rd 1.424 4th 1.000 5th 0.753 Reverse 3.431 Final 3.266
Basically it was designed to go faster and get better gas mileage, and it shows =)
more reading
https://www.clublexus.com/forums/sc-...io-thread.html
Doesn't seem like a big deal, but all of that translates into being able to achieve much better mileage than everyone at highway speeds because of the much lower final drive on the newer models even though the overdrive is very similar. This would make it a dog in the city though, which is why its paired with an extra gear that is much closer ratio 1-4. This is how the newer SC400's get crazy gas mileage on the highway.
1992-1997? Lexus SC 400 4.0L V8
A340E
Ratios 1st:2.804, 2nd:1.531, 3rd:1, 4th:0.705, Reverse: 2.39300 Final 3.916
1998?-2000 Lexus SC400
A650E
Gear Ratios: 1st 3.357 2nd 2.180 3rd 1.424 4th 1.000 5th 0.753 Reverse 3.431 Final 3.266
Basically it was designed to go faster and get better gas mileage, and it shows =)
more reading
https://www.clublexus.com/forums/sc-...io-thread.html
Last edited by Ali SC3; 08-12-13 at 11:12 AM.
08-12-13, 11:37 AM
#7
the gear ratios may be more favorable in the newer SCs but it still doesn't overcome the physics of the situation - its a 3600 lb beast with decent aerodynamics. it will not get 36 mpg at 85 mph. Power required goes up as a square of the velocity to overcome drag. Even a prius, a very aerodynamic and efficient car, drops below 40 mpg at 80 mph (look at this graph http://hiwaay.net/~bzwilson/prius/pri_2010_800.jpg)
Last edited by estomax; 08-12-13 at 11:40 AM.
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08-12-13, 11:53 AM
#8
I think you can't really compare a Prius to the SC400 since it's a 4 banger, meaning it has to maintain a high RPM at that speed which just opens up all the valves the entire time. If you're familiar with the Atkinson cycle engine, which most hybrids have, you'd understand that it's only good in city driving that's why salesmen in dealerships ask if you're gonna use the car more in city or freeway.
08-12-13, 12:10 PM
#9
guys a prius along with most cars are geared to be most economic around 40-60mph. after that it drops off sharply in my rx300 the mpg thing falls drastically as soon as you go near or over 70, because engine is revved up out of its efficiency zone. a vvti 1uz can move the beast along at highway speeds at a low rpm, and once the engineers added in that extra gear they were able to shift the efficiency curve to the right and also raise the top speed. lowering the final drive will give you better efficiency at higher speeds, its moves it to the right, raising the final drive will do the opposite.
with 4 gears there is not many ways to be efficient in both the city and at really high speeds, but with 5 or even 6 it becomes very easy. most luxury cars nowadays are designed to get better mileage at higher speeds, while all the econo cars are still geared to get you the most in the city and around 60 but not much higher than that.
If the prius was designed to cruise much faster than that, it would have come with some real wheels.
try driving around with overdrive off and see how much mileage you get @60. then try it with overdrive on and see how much you get at the same speed. The difference there will be similar to the difference between an older SC400 and a newer sc400, because the 5 spd literally has an extra gear over the old one.
with 4 gears there is not many ways to be efficient in both the city and at really high speeds, but with 5 or even 6 it becomes very easy. most luxury cars nowadays are designed to get better mileage at higher speeds, while all the econo cars are still geared to get you the most in the city and around 60 but not much higher than that.
If the prius was designed to cruise much faster than that, it would have come with some real wheels.
try driving around with overdrive off and see how much mileage you get @60. then try it with overdrive on and see how much you get at the same speed. The difference there will be similar to the difference between an older SC400 and a newer sc400, because the 5 spd literally has an extra gear over the old one.
Last edited by Ali SC3; 08-12-13 at 12:17 PM.
08-12-13, 01:15 PM
#12
I call B.S. Unless you're doing all highway miles, and even then, I doubt you can get 34mpg on average. I have a 2000 SC400 as well, and while I do get better mpg than my 92 SC400, it's nowhere near that level. Right now, with a combined city/hwy mix, I average 21-22mpg. My highest was around 26mpg. And my car is also low miles, bought it with only 48,500 on the clock and the mpg has stayed consistent up till now at 72,xxx miles.
08-12-13, 03:42 PM
#14
Prius or not, physics still exists and wind resistance doesn't go up linearly. Read here, its about cars and energy: linking isn't allowed so just Google "makes his power consumption 8 times smaller" and look at the first two links. From that article: "To go twice as fast requires eight times as much engine power."
At 85 mph you have to use a lot of energy, no matter the gearing and RPM. Another example for the 4 cyl vs 8 cyl argument is the brand new stingray corvette, that gets 30 mpg highway rated by EPA, which is impressive, but nowhere near 36 mpg @ 85 that our OP is claiming.
Last edited by estomax; 08-12-13 at 03:53 PM.
08-12-13, 05:02 PM
#15
Gotta call bravo sierra on this one. I have a '99 SC400 and get around 13mpg city and 20ish highway. I do have an intake, headers and straight piped exhaust but I never got the kinda mileage you're getting when mine was bone stock. Always use 93 and also drive it like i stole it.