What's interesting is I think you get better MPG at 75 than 55 in my LX... I still am shocked that I got 21MPG with an LX570 over 700 miles. In the city it's as awful as you'd expect OTOH lol. 12-13 max.

 

 

Unless you have a V-8!

The bigger engines drink gas when going slow or idling in bumper to bumper city traffic.

My RX330 with a V6 gets 25 on the highway and 13-14 mpg in town with AC running.

This is why the V8 lays down the miles per gallon on the highway.

It barely working hard on the highway and the mpg proves it. IMO

 

Again, you can’t defy the laws of physics . Big SUVs have the aerodynamic efficiency of a brick as it is, and there’s a massive increase in aerodynamic drag as speed increases. And there’s only one thing at the SUVs disposal to overcome that drag. Fuel. You don’t get better fuel economy in a big SUV at 75mph than you do at 55mph.

 

Areas with 55 mph speed limits are more likely to have stops and starts than areas with 75 mph speed limits and this might be factoring into it. At least out here, 55 mph is non-controlled access speed. You can people entering and exiting the highway, stop lights, etc. Generally a lot more interruptions to the flow of traffic than a road with a 75 mph limit.

 

https://streamable.com/ikmvue

The real reason we drive V8's

 

LOL exactly. And the drop off is huge. Even in my Pacifica. Fuel economy at 75-80 is DRAMATICALLY worse than at 65.

 

Lol okay, maybe I'm wrong. But it seems that way to me. In any case, I'm thrilled with the highway mileage of a truck with an engine that has zero fuel economy bs tricks (thank god).

And Striker didn't mean Brett's 5.0 gets 22MPG combined, he meant he gets it on the highway which I'm sure he does... if I'm getting 21 in one of the trucks that are the worst in the city a newer 5.0 absolutely does I would assume.

V8s barely have to work on the highway, whereas a heavy truck will be into the boost more. I think it downshifted out of high gear maybe twice the whole way up here, or I had the need for it. Just to accelerate in high gear 10mph or so without a downshift will require boost with a turbo engine.

 

Thats not what he meant lol. I said that it could get 22 on the highway, he meant they get 22 over normal driving over 10,000 miles when the EV that edmunds had gotten 19.9

 

Yep. Is that yours?? I hear cooling fans when I start LX but lol it’s obvious a big V8 is lurking under the hood.

It’s our Mercedes that sounds the best at the startup.

 

Wind resistance increases exponentially with speed if I remember right.

So it's more of an aerodynamic issue and gearing to an extent at higher speeds.

 

Yep, resistance from aerodynamic drag increases proportional to the square of speed. Unless you're (dramatically) altering the frontal area and/or drag coefficient along the way, the faster you go the greater the aerodynamic drag relative to speed, so the more force is required to overcome the drag, and that can only come from fuel hence it's a key reason that your fuel economy suffers the faster you go. At higher speeds it's a massive contributor.

75mph is a 36.36% increase in speed from 55mph. The difference in aerodynamic drag, however, is much greater at 75mph compared to 55mph (because it's proportional to the square of speed)

 

Correct. 36% more speed, 86% more drag. To further underscore how big of a difference speed makes, add another 5mph, and compare 55 to 80. 45% more speed, 112% more drag. For an incremental change of 9% in one metric, the other swells by 26%.

 

I got that 21 mpg over 700 miles from speeds 65-77ish.

I’ll start lot driving 55 on the way home for an hour or so and see what’s what.

I really don’t think it will be 20.9 going slower, but we’ll see. Even with drag you have to figure in engine RPMs, gearing, etc. LX570 purrs way better at 70 vs 50.

 

You can’t beat physics. At higher speed the main issue is aerodynamic drag, it also runs lower RPMs at 50 than 70 so none of that makes any sense.