Speed vs. MPG charts (post 'em if you got 'em)

[PaleMelanesian]

Sigh. I was driving when those numbers were taken. We sent Pickuptrucks a correction but they didn't change the table. The 40 mph reading was in 5th gear, not 6th. That's why it's lower mpg than 45 mph.

I was very impressed with how the loaded truck could hold top gear right at 45 mph even climbing hills with a full load. It just spun up the turbos and boosted the power while keeping rpm down at 1200. Nice!

[PaleMelanesian]

I got some numbers in my 2009 Fit Sport manual.

EPA 33 highway
2800 rpm @ 60
85F, humid, light wind
2-mile stretch of straight flat highway, cruise control
Numbers from a calibrated Scangauge, average of both directions

[MetroMPG]

Thank you, sir!

PS: hitting the EPA rating at 70 mph is pretty impressive. Evidence that not all automakers "push" their estimates.

[PaleMelanesian]

For the record, that's slightly (~3%) better than the 38 mpg rated '11 Fiesta I tested. Similar engine size, power, vehicle size/shape/weight, gear ratios, etc.

[gone-ot]

Originally Posted by PaleMelanesian

I got some numbers in my 2009 Fit Sport manual.

EPA 33 highway
2800 rpm @ 60
85F, humid, light wind
2-mile stretch of straight flat highway, cruise control
Numbers from a calibrated Scangauge, average of both directions

Curious, what was the engine rpm in 4th at that ~57± mpg number? Trying to numeralize the "loss" between 4th and 5th gear.

[PaleMelanesian]

~1500 in 5th, ~1900 in 4th.

[PaleMelanesian]

I went out and burned another half gallon getting more numbers. This time on a low-speed road. Similar conditions, and I ran the 40 mph segment again for comparison. Nearly identical results so I'll say they're valid. I averaged both days into the 4th and 5th gear, 30 and 40 mph numbers.

[justme1969]

sorry for hijacking the thread but that Fit looks like it would get tremendous gain from larger diameter drive tires.
It looked very linear mpg v/s mph drop I just see flattening out that line some.

[PaleMelanesian]

It would definitely benefit from lower rpm cruising. Not necessarily bigger tires, because there are weight and aerodynamic and rotational inertia penalties involved there. Just look at the RPM vs MPG chart and imagine what a 6th gear would look like. I want one.

[Blue Angel]

This was my first attempt at logging some speed vs. consumption data. I used the on board mileage computer corrected at 7% as it is optimistic, so these should be pretty close. Two different roads used, one for low speed and the other for high, both relatively level and in calm conditions, temps between 16C-18C, two way averages.

The car is a '12 Eco with a manual transmission. Modifications are higher tire pressure, lowering springs, wider plug gaps (0.033") and 91 octane fuel. The only mod that's guaranteed to increase efficiency is the tire pressure, but the car already has LRR tires. Lowering the car reduces its frontal area, but the suspension geometry of the Cruze adds significant negative camber to the front tires as the car gets lower, which will likely increase rolling resistance.

Speeds were in increments of 10km/h between 50-100, but converted to MPH on the chart. Speeds and MPG seem to relate fairly closely to the Motortrend chart from the review posted earler at both 50 MPH and 60 (62) MPH.

Next time out I will try to do highway runs at 110 and 120 km/h as well.