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Old Jul 27, 2022 | 12:32 PM
  #1081  
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Originally Posted by Lwerewolf
Vehicle weight doesn't matter anywhere near as much as drag at high speeds.
Vehicle weight absolutely matters. Big time. Lexus V8 historically had better gearing than a V6. Get all the Apples to Apples in a comparison, and a smaller 6 will burn less fuel.

this is the only one I can think of




Last edited by Toys4RJill; Jul 27, 2022 at 12:37 PM.
Old Jul 27, 2022 | 12:38 PM
  #1082  
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Originally Posted by LexsCTJill
EPA is 2 mpg difference. Sure it is possible to be the same depending on driving style, but I trust EPA
You know, it might have actually been a tad worse than the V8. My spouse drives like a Grandmother, wouldn't matter if it was a 150hp 4 cylinder.

When I'd check the tank average sometimes it would be in the high 16s. LS430 I can get mid to high 17 MPGs in the city.

I don't really trust EPA for real world. Remember I also get 3 more on the highway than rated with the truck.
Old Jul 27, 2022 | 12:41 PM
  #1083  
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Originally Posted by LexsCTJill
Vehicle weight absolutely matters. Big time. Lexus V8 historically had better gearing than a V6. Get all the Apples to Apples in a comparison, and a smaller 6 will burn less fuel.

this is the only one I can think of
Check out how fast an SUV's fuel consumption climbs at speeds above 60mph. At 80+ they can easily be matched or beaten by a heavier sedan.

A smaller engine absolutely can be beaten by a bigger engine if you require a load that's beyond the smaller engine's sweet spot, if the smaller engine has to stay heavily throttled at high RPM due to gearing (*cough* 2IS350 *cough*) and so on.

Cylinder count doesn't matter.
Old Jul 27, 2022 | 12:43 PM
  #1084  
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Originally Posted by Lwerewolf
Perhaps you can share BSFC figures to back that claim?



Just tested:
Grade: 22.7%
Altitude: 732m min, 749m max
Distance: 3.644km
GPS Speed: 149km/h constant (cruise control), ~92.5mph
RPM: 2187rpm (avg), 2510rpm (max)
Power: 54.13kw (avg), 63.46kw (max)

No SoC change (read: no power going out of the battery). Outside temp 29C, AC set to 24.

4000rpm is around 125kw sustained power output. This car does not generally see >2000rpm during steady state cruising on the highway, unless traffic allows for such speed and I'm in the hilly section.

Aerodynamics:
https://www.automobile-catalog.com/c...i_quattro.html
https://www.automobile-catalog.com/c...s_gs_450h.html
both claimed 0.27 cd/m2, slightly larger cross section on the A8.

Still not convinced that any such car does 29mpg (~8.11l/km) at 90mph (~145kph).
I have a GS460, before I lowered it, change the wheels (bigger and wider), changing the TCU and added front lip I was easily getting 30 mpg at 90 mph. I was blown away, because strangely at 75 mph it would only get 1 mpg better. After the mods I get around 24-25 mpg at 90 mph. Not sure what exactly has been the biggest factor for my reduced mileage, probably just a combination. I'm in florida though so roads are flat.
Old Jul 27, 2022 | 12:48 PM
  #1085  
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30mpg at 90mph using cruise control, on a reasonably large round trip (say, 20+ miles), both ways, consistently (to avoid "luck" with wind and so on)?
Old Jul 27, 2022 | 12:49 PM
  #1086  
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Originally Posted by Lwerewolf
Check out how fast an SUV's fuel consumption climbs at speeds above 60mph. At 80+ they can easily be matched or beaten by a heavier sedan.
r.
100%. but, we are talking apple to apples, not an SUV vs heavier sedan (very rare for a Lexus sedan to be heavier than a Lexus SUV GX/LX) ... we are talking Lexus larger engines vs smaller engines. There is no EPA data that I am aware of that would support/demonstrate this.

Last edited by Toys4RJill; Jul 27, 2022 at 12:52 PM.
Old Jul 27, 2022 | 12:51 PM
  #1087  
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Originally Posted by Lwerewolf
Vehicle weight doesn't matter anywhere near as much as drag at high speeds.

Engine tuning is exactly what I described with the fuel per work measurement
. https://en.wikipedia.org/wiki/Brake-...el_consumption
True about the weight when not accelerating, I agree.
Checked out the link and good stuff there.

Noticed the equation suggests it's all about the Torque.
I'm guesing that would all depend on the car and what speed and gearing they have to achieve max torque and efficiency.

Here's the equation from the link.




Originally Posted by LexsCTJill
There is far more to that. Vehicle weight. Aerodynamics. Engine tuning...
Absolutely.

Originally Posted by SW17LS
My S560 gets great mileage...
There's OP.
Approx what you get.
Guessing the S560 is a 5.6L
Old Jul 27, 2022 | 12:59 PM
  #1088  
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You can find some BSFC graphs for certain engines if you look. Peak torque might be a bit misleading.
Old Jul 27, 2022 | 01:01 PM
  #1089  
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Originally Posted by Margate330
Guessing the S560 is a 5.6L
It should be, but it's not. That said the 4.0tt is a screamer.
Old Jul 27, 2022 | 01:06 PM
  #1090  
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Originally Posted by Lwerewolf
You can find some BSFC graphs for certain engines if you look. Peak torque might be a bit misleading.
Yeah I can see that.
What they like to drive in Belgium aka whats popular and what cars people want?

Originally Posted by AJT123
It should be, but it's not. That said the 4.0tt is a screamer.
Thank you ATJ.
It used to be easy to see what's under a hood.
Duh my RX330 is a 3.3L, oh the good days.
I bet a 4.0L twin turbo does scream, sounds like fun.
Old Jul 27, 2022 | 01:38 PM
  #1091  
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Originally Posted by Lwerewolf
Check out how fast an SUV's fuel consumption climbs at speeds above 60mph. At 80+ they can easily be matched or beaten by a heavier sedan.

A smaller engine absolutely can be beaten by a bigger engine if you require a load that's beyond the smaller engine's sweet spot, if the smaller engine has to stay heavily throttled at high RPM due to gearing (*cough* 2IS350 *cough*) and so on.

Cylinder count doesn't matter.
I can attest to that, previously owning a 2010 IS350 Sport. Very short gearing. At 80 MPH I was around 2600 RPM. My 2006 Camry SE (3.3L V6) with a 5 speed I was at a much lower RPM at the same speed, and my 2013 Sienna with a 6 speed auto I'm probably 2200 RPM at 80 mph
Old Jul 27, 2022 | 02:09 PM
  #1092  
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Originally Posted by LexsCTJill
No way those 8 cylinders are more fuel efficient compared to the same generation engine but slightly smaller
They 1000% are at 70+. No comparison since the rest of the car is so much better in terms of overall system efficiency. Remember, I also own a 07 ES350.....it can't come close
Old Jul 27, 2022 | 02:10 PM
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Originally Posted by LexsCTJill
EPA is 2 mpg difference. Sure it is possible to be the same depending on driving style, but I trust EPA
EPA is at 55mph. That should be all I need to say.
Old Jul 27, 2022 | 02:11 PM
  #1094  
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Originally Posted by Lwerewolf
Check out how fast an SUV's fuel consumption climbs at speeds above 60mph. At 80+ they can easily be matched or beaten by a heavier sedan.

A smaller engine absolutely can be beaten by a bigger engine if you require a load that's beyond the smaller engine's sweet spot, if the smaller engine has to stay heavily throttled at high RPM due to gearing (*cough* 2IS350 *cough*) and so on.

Cylinder count doesn't matter.
This. The 8s simply do not need to operate outside of their peak BSFC curve like a 6 would be forced to.
Old Jul 27, 2022 | 02:12 PM
  #1095  
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Originally Posted by Blaze876
I have a GS460, before I lowered it, change the wheels (bigger and wider), changing the TCU and added front lip I was easily getting 30 mpg at 90 mph. I was blown away, because strangely at 75 mph it would only get 1 mpg better. After the mods I get around 24-25 mpg at 90 mph. Not sure what exactly has been the biggest factor for my reduced mileage, probably just a combination. I'm in florida though so roads are flat.
That lip would MURDER your aero.....like horribly so.



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