swirlygirls
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Post by swirlygirls on Mar 7, 2016 6:08:59 GMT -8
I'm a towing newbie so this is a most basic question. This past weekend I took my trailer on a road trip, 2 1/2 hours each way. First day was not windy and roads were dry. I had a sway bar on but I think I didn't have it tightened quite enough. Gas mileage was 14.6. On the way home several variables changed. (Speed wasn't one of them, if anything I went just a bit slower on the return trip.) t tightened the sway bar, had a head wind, and it rained part of the way. Gas mileage 10.6. Now that was painful. Which one of those variables caused such a significant decrease in mpg? I'm assuming the sway bar didn't have anything to do with it but that the wind was the big culprit. Is that normal? Thank you for the feedback.
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turbodaddy
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Post by turbodaddy on Mar 7, 2016 6:27:21 GMT -8
I'm guessing "headwind", definitely a factor with our FAN which is not at all aerodynamically designed! But it sure is comfy.
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Post by bigbill on Mar 7, 2016 7:18:26 GMT -8
The smaller the engine and the higher your drive gear ratio (lower numerically) the more a head wind will cause your fuel mileage to drop. This is why one person buys a certain tow vehicle and loves it but someone else buys the same model but hates its performance. This is a major variable in light trucks, vans and SUVs more so than others. Both of these factors requires you to increase your throttle setting under more load (head wind) which means your mileage will drop.
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Post by bigbill on Mar 7, 2016 7:24:37 GMT -8
Also if you are towing in overdrive try towing in drive if there is factors increasing resistance such as head winds and hills. Most vehicles tell you to never tow in overdrive because of the extra strain of towing. Read your owners manual for towing suggestions it might help. This is another reason to never tow more than 50% of towing capacity.
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turbodaddy
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Post by turbodaddy on Mar 7, 2016 13:32:07 GMT -8
Bigbill, that is something a lot of people might be confused about, thanks for bringing it up. I was confused because I have owned vehicles in the past that had a clearly marked button or switch called "overdrive". To clarify, today's vehicles may have something like this for shifting choices: This one has a circle around "D" which indicates overdrive. Here is another version: Then this with no clearly indicated overdrive, I'm guessing if you shift from "D" to "3", a digital indicator will light up on the dashboard "Overdrive off":
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turbodaddy
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Post by turbodaddy on Mar 7, 2016 13:34:07 GMT -8
Something went wrong with my post, I had photos of different shift indicators that did not load! I'll try again.
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Post by bigbill on Mar 7, 2016 17:04:32 GMT -8
Bigbill, that is something a lot of people might be confused about, thanks for bringing it up. I was confused because I have owned vehicles in the past that had a clearly marked button or switch called "overdrive". To clarify, today's vehicles may have something like this for shifting choices: This one has a circle around "D" which indicates overdrive. Here is another version: Then this with no clearly indicated overdrive, I'm guessing if you shift from "D" to "3", a digital indicator will light up on the dashboard "Overdrive off": I answered this in the new post, with a very general answer because of all the different transmissions out there.
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swirlygirls
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Post by swirlygirls on Mar 8, 2016 6:09:56 GMT -8
Thank you for your answers. I'm going to spend more quality time with my car's owners manual. The learning never stops!
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SusieQ
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Post by SusieQ on Mar 8, 2016 7:32:42 GMT -8
I experience the same thing when towing my Compact. Sometimes I get 18 on the way to my destination and sometimes it gets down as low as 12 on the way home, ugh. My average when I'm not towing is 26-28 on the highway. I can tow my teardrop and might lose 2 miles. The difference there being mostly aerodynamics, as they are close in weight but there is no headwind on my teardrop since it is lower than my vehicle. My vehicle knows when it is towing and automatically adjusts.
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SusieQ
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Post by SusieQ on Mar 9, 2016 7:44:04 GMT -8
One more thing, the biggest difference is speed. If I pick up even a couple of miles, the mileage goes down a couple of mpgs.
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Post by bigbill on Mar 9, 2016 13:49:35 GMT -8
One more thing, the biggest difference is speed. If I pick up even a couple of miles, the mileage goes down a couple of mpgs. Anything you do to increase resistance, such as speed, wind, car top racks, hills, or anything else will cause a decrease in gas mileage. Even using cruise control while towing can cut your mileage by increasing the throttle setting more than you might if you were controlling it yourself. Even though most automatic transmissions will down shift when the load increases enough most of the time selecting a lower gear sooner can actually save fuel if done properly. Each vehicle and driver is different so you have to figure out what works best for you and your rig.
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SusieQ
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Post by SusieQ on Mar 9, 2016 14:51:54 GMT -8
One more thing, the biggest difference is speed. If I pick up even a couple of miles, the mileage goes down a couple of mpgs. Even using cruise control while towing can cut your mileage by increasing the throttle setting more than you might if you were controlling it yourself. Even though most automatic transmissions will down shift when the load increases enough most of the time selecting a lower gear sooner can actually save fuel if done properly. Each vehicle and driver is different so you have to figure out what works best for you and your rig. It thought this, too about cruise control and I even asked the service manager at my dealership and told me not to tow with cruise on. Then I read my manual. It said you should use cruise when towing for optimum gas mileage with an exception if hills caused more than a 10 mile gain in speed. I've never had that happen. I've tried both ways. So it totally depends on the vehicle and the amount of tech it has. And even though my tranny can be shifted manually, it will not shift into an unsuitable gear.
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gary350
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We should have gone camping today it is going to snow 6" tonight.
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Post by gary350 on Mar 9, 2016 15:52:58 GMT -8
Every time your speed doubles wind resistance triples, that is the Laws of Physics.
If your driving 60 mph with no head wind that is equal to driving 50 with 10 mph head wind.
I can pull my camper up to 50 easy but anything faster is like pulling a parachute. My vehicle gets 18.5 mpg at 70 on the highway but with the camper trailer I get 9 mpg at 65. The slower I drive the better my gas mileage gets.
I am glad gas is no longer $3.50 per gallon.
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Post by bigbill on Mar 10, 2016 3:33:12 GMT -8
In regard to a couple of post: To my knowledge no automatic transmission will shift to a gear or stay in a gear beyond certain parameters unless it has been modified. As to gas prices everybody is glad the price of fuel is down, that is what severely wounded the RV and boat industry plus the sales of larger vehicles.
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swirlygirls
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Post by swirlygirls on Mar 10, 2016 5:48:07 GMT -8
So if the concepts of physics and drive gear ratios elude me, I will just remember to slow the hell down and hope gas prices don't rise. Thank you all!
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