[rustinn]

What speed gets you the best MPG in general and on the highway?

 

[jblackburn]

45 on my 1LT 6M. Don't really cruise consistently at any other speeds, but we have a few highways around here at that speed, and I've seen 52+ mpg indicated on the dash average display at those speeds.


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[rustinn]

Conventional wisdom tells me it'll come at 42 mph which is right when the car slips into 6th gear and the engine is moving at about 1500 rpm.

 

[cwerdna]

40 MPG Comparison Constant Speed Chart Photo 13 that I posted at http://www.cruzetalk.com/forum/27-f...-mpg-compact-sedan-comparison.html#post102658 might interest the OP.

 

[obermd]

40 MPG Comparison Constant Speed Chart Photo 13 that I posted at http://www.cruzetalk.com/forum/27-f...-mpg-compact-sedan-comparison.html#post102658 might interest the OP.

Although the Cruze used in this article is an ECO MT, the chart showing MPG vs. MPH works for all cars. Basically, the slower you can go while staying in 6th gear the better your MPG. Prior to seeing this article I had tested my ECO MT for fuel economy on various streets and roads with 45, 50, 55, 65, and 75 MPH speed limits. I hit the MPG numbers in the Motor Trend chart for the ECO MT. Measurements were with my DIC but I adjusted the numbers I got down by 5% as that seems to be the optimism for my car's DIC.

 

[OnlyTaurus]

I recently drove a 240 miles trip on Saturday. Got 51.2mpg averageing 60.3mph. Of course, I was drafting an 18-wheeler the whole time.. which helped.

 

[sciphi]

Best for speed on the highway for my Eco MT is 61 mph. A manual LT will be likely about 55 mph due to gearing. That's just under 1800 RPM where the turbo starts providing max torques.

1500 RPM in 6th, or about 48-49 mph, is superb for fuel economy. Adjust the speed down for a non-Eco MT.

 

[Rockerxink820]

so i been doing some long trips the last few week from pittsburg to cleveland its about 150m one way and w/o cruise control i was getting 43mpg @ 70mph

 

[obermd]

so i been doing some long trips the last few week from pittsburg to cleveland its about 150m one way and w/o cruise control i was getting 43mpg @ 70mph

Try it with cruze control on the same route and similar weather conditions. You'll get a couple more MPG. The ECU is far better than the foot on flat driving at maintaining speed while keeping average RPMs down. Also boost your tire pressure to at least 45 PSI (40 for the non-ECOs) if you can handle the slightly noisier ride and stiffer road feel. Don't go over the sidewall pressure, however. With these changes I get 42 MPG at 75-77 MPH. At 70 I get slightly over 45 MPG.

Altitude might be a factor as well. There's a lot less air to push through in Colorado than in Pennsylvania and Ohio.

 

[70AARCUDA]

Conventional wisdom tells me it'll come at 42 mph which is right when the car slips into 6th gear and the engine is moving at about 1500 rpm.

...exactly:

...the "hypermiler" driving mantra, "...in highest gear, at slowest speed, that doesn't lug the engine..." contains three distinct constraint regimes:

1) "...in highest gear," -- where engine loading & efficiency are highest.

2) "...at slowest speed," -- engine RPM affects loading & efficiency; this is transmission & axle ratios, and road speed!

3) "...that doesn't lug the engine." -- the "bottom" of the bathtub-curve; this is engine torque, and where higher fuel octane helps.

 

[XtremeRevolution]

Specific fuel consumption is best achieved when driving high engine throttle at the lowest RPMs possible.

Browser Warning

An early Cruze Eco was tested here:

CleanMPG Forums - GM’s Most Fuel Efficient Car Coming to Chicago

The results were as follows:

50 mph 51.7 mpgUS
55 mph 46.7 mpgUS
60 mph 44.2 mpgUS
65 mph 39.4 mpgUS

The conditions were terrible (freezing with strong side winds), so I would consider that to be the bare bottom of what one should get at those speeds in the Cruze Eco. It does however reinforce what has been said; highest gear at the lowest RPMs possible. The lower the speed, the less drag you will have to overcome. At 65mph, I've been able to average 56mpg per the DIC on a round trip, which, based on a ~5% optimism should put me right at around 52mpg had I calculated it at the pump.

 

[rustinn]

Interesting. Thanks for all the input guys.

 

[DrVette]

Depends on many factors, terrain being the most critocal.

On flAt ground, around 38-40 vields well over 60 "actual" mpg.
I can really try hard and get over 70 if there's no traffic to hold up.

I grabbed a shot of the DIC showing well over 70 for some 30 miles or so.
It only takes one little "oops" to kill figures like that.

Of course, in normal driving these mpg's are not realistic but it is nice to know what you can get if gas gets really high or rationed.

 

[XtremeAaron]

I just did a 155 mile round trip yesterday and hit this all time best for me by the time I made it home last night. The first 53-54 miles were city driving, stop and go. AC the entire time, 69 MPH on the highway, set to cruze. Terrain remained relatively flat, little to no wind. Needless to say I was very impressed. It kept climbing too, but I didnt have a chance to snap a pic because some idiot pissed me off the turbo spooled and off I went.

View attachment 6829

 

[rustinn]

That's actually pretty reasonable.

 

[CruzeTech]

Driving a 106 mile round trip. Cruise @ 72. I got 43.2.


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[XtremeRevolution]

Driving a 106 mile round trip. Cruise @ 72. I got 43.2.


Sent from my Autoguide iPhone app

Same. The Eco MT is a whole different animal than the auto Cruzes. Going 60-65mph with steady traffic (not being the only one on the road), I regularly average ~55mpg according to the DIC.

 

[spacedout]

Depends on many factors, terrain being the most critical.

Actually with most hills what you loose in MPG you will gain on the downhill side coasting(thanks to DFCO), a few exceptions, extreme grades, hills larger than 300ft elevation change, & super long grades that keep the car under heavy load for miles. In those conditions I have to have a very easy route for at least 3-5miles after the hill to gain back all I have lost according to the DIC.

Stop signs & stop lights are almost as bad as it take a ton of energy to get a car moving again. Best bet is to pick a route with very few hills & eliminate as many stop signs/lights as possible. If you can't eliminate stops you can find routes with more miles between stops. that way even though the acceleration takes your average MPG down, a longer section at steady speed between stops/turns should bring your MPG average back up.

 

[gman19]

I get my best running about 45-48 mph.
Last tank was a 566 mile tank, 41.15mpg, average speed 34.5mph.

Snapped these before and after my fill-up:

 

[obermd]

At highway speeds, wind plays a huge factor in MPG. Headwinds effectively add to the car's speed. Tailwinds subtract from it. The ECO MT, at least, is very sensitive to this effect.