Road trip fuel mileage report.

[TorqueMan]

Had to take a recent 2600+ mile road trip to deal with a family issue, so I decided to keep records on fuel economy for $h!ts and giggles. My car is bone stock (except for the fancy shift knob) with approx 25K miles. I use Wally-world brand (Super Tech) 5-30 full synthetic oil, changed every 5K. I ran premium (91 octane or better) for the entire trip. Below is a chart of the data I recorded:

Here are a couple of things that jumped out at me when I looked at the data.

The data confirm the EPA fuel economy estimate for my car is spot on. The window sticker says I should get 31 mpg highway. The data also confirms economy is strongly impacted by wind. Leg 2 was the only portion of the trip with a headwind, and the mileage for that leg is the worst. Additionally, all the legs at higher altitudes produces excellent mileage despite the higher cruising speeds. I believe this is because turbocharging ensures sea-level performance from the engine despite the thinner air, while the thinner air (atmospheric pressure at 5000' is approximately 80% of sea level) reduces wind resistance. This is especially apparent on Leg 5, where I was cruising across Wyoming on I80. I had the cruise set at 88 MPH (10% above the 80 MPH speed limit) for much of that leg, yet still saw 31+ mpg.

The data also confirmed the computer-indicated fuel economy is optimistic, consistently indicating 1 - 1.5 mpg higher than actual.

Feel free to ask any questions. I'm curious if any of you see anything in the data that I didn't.

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[Interceptor]

Was the fuel same brand and rating?

 

[TorqueMan]

Was the fuel same brand and rating?

Fuel was 91 or 93 octane, but from a variety of suppliers. 93 octane is hard to find in the mountain states. Suppliers were typically truck stops or travel plazas selling top tier brand gasoline.

 

[Cardude99]

Do you have the pp or no? Wondering what your gearing is, as I have the 3.55 and it kills my mileage

 

[TorqueMan]

Do you have the pp or no? Wondering what your gearing is, as I have the 3.55 and it kills my mileage

Not PP, so 3.31 gears. Mine's also a manual trans. IIRC, EPA says 3.55 gears should yield 29 mpg on the highway, which is two less than estimates for cars with higher gearing.

I typically see 28 - 29 mpg in 80/20 mixed highway/city driving during the summer. That drops to 26 - 28 in the winter. This car seems very sensitive to cold starts.

 

[Cardude99]

I remember driving a base model non pp. I got around 34mpg at 80 with that. It was wonderful, best I can manage on my car at 80 is 28.5. not terrible but not 34 either

 

[FreedomPenguin]

3.31 is nice, I am getting 34mpg at 70sh all day, non PP manual.

 

[Redcruzer]

How did cruise control factor in? (Or did it?) I did a 1500 mile trip, pre tune, with varied terrain and got 31.4 on the dash with a vert and 3,31’s. I noticed a big difference using the cruise control.

 

[TorqueMan]

How did cruise control factor in? (Or did it?) I did a 1500 mile trip, pre tune, with varied terrain and got 31.4 on the dash with a vert and 3,31’s. I noticed a big difference using the cruise control.

I used the cruise control to the maximum extent possible, mainly to prevent fatigue, so I can't really tell you if there's is difference without using it. I would imagine any difference would depend on how dilligent you are at maintaining speed. If you are as good as the cruise control then there shouldn't be a difference.

 

[law242]

I am lucky to get 22 avg mgp on mine... Wish I knew why mine is so different from people who get this amazing fuel economy

 

[TorqueMan]

I am lucky to get 22 avg mgp on mine... Wish I knew why mine is so different from people who get this amazing fuel economy

Is that mostly highway, mostly city, or 50/50? A lot of cold starts and short trips have a big effect on mileage for me. For example, I used to leave the office for a lunch break daily. Just doing that cost nearly 3 mpg on a tankful, in the winter it's more like 4 mpg. The car is also sensitive to acceleration. Don't forget it weighs 3600+ lbs, and accelerating that much mass quickly it costs fuel. The harder you accelerate, the more fuel. Many have noted you either get "eco" or you get "boost," but never both.

Keep in mind this entire trip was highway driving. The only city driving was on and off the exit to get to the highway.

 

[law242]

I can understand all this, mostly 50-50 driving for me. and Yes going to lunch and getting food, or ill leave the car idling when I walk into a gas station. So I know it could be better. Economy went up on a small road trip, will say that

 

[TicTocTach]

Great results - and very familiar looking tracking going on there...

My EBPP (3.55/A10) is averaging a little over 22mpg over 11k miles to date. My commute is about 1/3 city streets and 2/3 highway @ 80mph or 8mph. I also take advantage of the ability to pass slower traffic now that I can, and I play with the car when I have to run any errands. I'd love to get 25mpg in town and 35mpg on the highway like my previous Honda Fit used to get, but with 200% more HP and 50% more weight, I'm reasonably pleased the mileage. I will add that on the highway for extended road trips, mileage will reach past 30mpg if I can stay 70mph or lower. That just doesn't happen much in TX where posted speed limits are 70 or 75mph, and actual driving speeds are 80+ if you stay with traffic. Best actual mileage to date is 28.45mpg.

 

[jdsfly]

I just finished an 800 mile trip and averaged 36 mpg. I have a 2018 EB A10 with 3.15 gears. I used 87 octane and ran mostly 70-75 mph.

 

[TorqueMan]

I just finished an 800 mile trip and averaged 36 mpg. I have a 2018 EB A10 with 3.15 gears. I used 87 octane and ran mostly 70-75 mph.

Questions:

1. Was your average computed by the car or by hand?
2. Altitude?

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