The most economical speed for the Yaris.

[Ilovemyyaris]

Hello everyone. I was reading some comments on yahoo news about saving gas and I was reading the comments when I ran across a comment that said this

i love it when people who know nothing about cars and physics write articles on fuel consumption. your manufacturer can recommend a cruising speed to optimize your fuel consumption. not all vehicles will get better mileage by reducing speed. . . and according to the article. . . reducing speed from what base speed? not all vehicles (with different weights, consumption and compression ratios) are going to get the same mileage at the same speed. some of which you might not being driving fast enough, for instance a heavy vehicle may need a faster speed to maintain momentum versus its compression ratio.

And followed by other commenters.

Here's an experiment I did with my '96 Honda Accord 4 cylinder going from Los Angeles to Mammoth Lakes, about 300 miles one way through the desert.

65 mph - 30 mpg
70 mph - 32 mpg
75 mph - 33 mpg
80 mph - 32 mpg
85 mph - 26 mpg
90 mph - 21 mpg

Since then, I NEVER drive faster than 80... I try to go in the 70 mph range depending on traffic and conditions... YMMV...

To say it another way, at say 2000RPM, a given engine in going to use "x" number of gallons per minute, regardless of how fast the car is going. Depending on what gear you are in, your care may able to go say 45mph, 55mph, and 65mph all at 2000RPM. Simple math will tell you that if you are going 65mph at 2000 RPM, you will use less fuel than if you are doing 45 at 2000.

My pick-up gets the best gas milage at about 53 MPH. It up shifts between 50 and 55, and I can maintain 53mph, with an RPM of about 1200. I let the RPM drop a little, and I down shift, RPM jumps to about 2000, and I settle at about 51mph.

JohnA-you are wrong. I have monitored my gas, I absolutely get better mpg at 65 than 55. Seventies is even better. This was confirmed when I asked my mechanic, and he said the car was designed to travel at higher speeds.

Exactly. My 2011 Diesel F250 in 5th gear at 40 mph gets about 14 mpg and after hitting 50 mph and it shifts into 6th gear it gets about 20 mpg.

So I was wondering is there a specific speed for the Yaris to achieve the most optimal mpg?
I know it's low RPM in the highest gear right? My Yaris doesn't have an RPM gauge so I can only tell by how loud the engine sounds and I can't really tell. I think I hear it the softest at 45-50 mph I generally go about 55-60 on the highway.