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U.S. highway cruising speed

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Joined
May 4, 2023
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107
Location
North Texas
Does anyone know if the design balance with off-road and highway travel allows an efficient cruise? What I’m getting at is - I’m in North Texas and moving along at 75-80 mph is daily on the highway/interstate to get between Point A and Point B. Does the power to weight aspect allow this or is it something to be determined, and is a negative effect on MPG? Probably too early to tell.. Thanks.
 
Does anyone know if the design balance with off-road and highway travel allows an efficient cruise? What I’m getting at is - I’m in North Texas and moving along at 75-80 mph is daily on the highway/interstate to get between Point A and Point B. Does the power to weight aspect allow this or is it something to be determined, and is a negative effect on MPG? Probably too early to tell.. Thanks.
 
It is not a EV. I don’t own one yet but I would suspect best cruising speed is somewhere around 70. At best you should hope for 15-20 mpg at any speed. Power will be more than enough
 
Does anyone know if the design balance with off-road and highway travel allows an efficient cruise? What I’m getting at is - I’m in North Texas and moving along at 75-80 mph is daily on the highway/interstate to get between Point A and Point B. Does the power to weight aspect allow this or is it something to be determined, and is a negative effect on MPG? Probably too early to tell.. Thanks.
Pushing a brick through the air isn't going to be fuel efficient. Also, I've noticed in my Kia that there's a sweet spot around 75, which is the new 55 that was around for decades. Going over 75 increasingly drains the tank. The faster you go, the faster the fuel gauge drops.
 
Does anyone know if the design balance with off-road and highway travel allows an efficient cruise? What I’m getting at is - I’m in North Texas and moving along at 75-80 mph is daily on the highway/interstate to get between Point A and Point B. Does the power to weight aspect allow this or is it something to be determined, and is a negative effect on MPG? Probably too early to tell.. Thanks.
As mentioned, the Grenadier has the drag coefficient of a brick. Drag increases according to the inverse square law...double the speed and the (aerodynamic) drag /wind resistance increase x4. This becomes significant above 50 mph. At 75-80 mph the rpm is approx. 2100-2300 rpm in top gear which is well into the flat torque curve (1750rpm-4000rpm for the B58 petrol engine), so the vehicle should pull like a freight train in 6th, 7th and 8th gear at those speeds! However, at 80mph the drag is approximately 2 1/2 times the drag at 50mph with a significant increase in fuel consumption. 3 tonnes is a healthy mass to steer at approx. 120 feet per second!
 
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My old Defender 110 the same shape as a Grenadier had a sweet spot at about 65mph

The Grenadier should be better because it's higher geared in cruise. At 65mph the Defender was at about 2,700 rpm
 
It cruses at 70 no problem even 80 but the drag goes up with the square of the speed so you have choices but there is plenty of power there what ever engine choice .
 
Everybody who has his own sweet spot at 70 or 80 mph should really test the car (not only the Grenadier) on a longer run with different speeds but same conditions (freight/weather/tyre pressure).
The real sweet spot will be somewhere between 55 and 85 km/h (35 - 55 mph). As DenisM wrote, you can not trick the drag. of course a Corvette might have the sweet spot at a higher speed. But generally you can take the highest gear with the lowest rpm possible for smooth driving. Somewhere there will be the best speed for driving most economic. I didnt calculate that for the Grenadier, but I am sure someone will.
 
Does anyone know if the design balance with off-road and highway travel allows an efficient cruise? What I’m getting at is - I’m in North Texas and moving along at 75-80 mph is daily on the highway/interstate to get between Point A and Point B. Does the power to weight aspect allow this or is it something to be determined, and is a negative effect on MPG? Probably too early to tell.. Thanks.
You will be driving a vehicle that has the aerodynamics of a washing machine - so the milage looks abysmal for normal 15MPG and at 70-80 mph it will be much worse. I had a Cayenne Turbo for 3 years and loved it - especially the sound - but the better it sounded (high revs/speed) the milage was horrific....I think I was averaging 12mpg at best...
 
l've currently got a new Defender which isn't exactly aerodynamic and at around 70mph l can get close to 40mpg.

lt's a similar engine to the Grenadier (3.0 Diesel MHEV) and similar weight.

l wouldn't expect the Grenadier diesel to match that, because of the more traditional drivetrain and original Defender style bodywork but at a steady 60mph l am willing to bet it will do over 30mpg.
 
Also l am talking U.K. gallons which are larger than US gallons of course.

A U.K. gallon is 4.5 litres while a US gallon is 3.7 litres.

So if you are getting 20mpg in the US that's equivalent to around 25mpg in the U.K.
 
Maybe something more military? A troop, platoon, etc?
 
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