Which is more wise

[caineroad]

If I were have to run a 400km straight road, in terms of fuel efficiency. Which one would be better? No a/c, drag or whatever other factors involved.

Yaris going at
160kph/100mph = 2.5Hrs

Or
80kph/50mph = 5Hrs

The rule is to save as much fuel as possible.

Cheers:bow:

[Betrivent]

80

[WeeYari]

??????

160kph for 2.5 hrs = road side suspension

What are you getting at here?

[caineroad]

Despite the road limit. 80?

[Brentorius]

80kph/50mph = 5Hrs
If you are trying to use as little fuel possible, stick with the speed that nets you more mpg.

[caineroad]

80kph/50mph = 5Hrs
If you are trying to use as little fuel possible, stick with the speed that nets you more mpg.

What's the speed I get the most mpg?

[supmet]

What's the speed I get the most mpg?

45 mph

[caineroad]

45mph = approx 70kph

Thanks

[BailOut]

What's the speed I get the most mpg?
Somewhere between 35 and 45 MPH, depending on the road and weather conditions, and any elevation changes.

[ddongbap]

You forget wind resistance. Higher the speed, the more it sucks.

[IllusionX]

60kmh in 5th gear is the best fuel saver. But you have no choice but to go faster at the slightest incline.

[Yaris Hilton]

If I were have to run a 400km straight road, in terms of fuel efficiency. Which one would be better? No a/c, drag or whatever other factors involved.

It's quite impossible to exclude drag, or "whatever other factors [are] involved."

The correct answer has been given several times already.