3.0L Diesel, 47 MPG US
 

I recently did a road trip from Oakville, Ontario, Canada (home) to visit a friend in Colorado Springs, Colorado. Here are some fun facts:

• Vehicle: 2015 Audi Q5 mid-size SUV, 3.0L diesel, 8-speed auto, full-time AWD, tires inflated to recommended 32 PSI. 1 occupant (me) @ 175 lbs. Ambient air temp ranged from 48'F to 76'F. A/C used for less than 6 hours.
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• Distance: approx 2,550 km (~1,580 miles) 1-way
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• Elevation difference: Oakville 567 ft ASL, Colorado ~6,400 ft
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• Typical Speed: 80 KPH (50 MPH) -- 55 MPH in Michigan (legal minimum)
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• When traffic was reduced to a single lane in construction zones, I did the speed limit, typically 60 MPH.
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• Almost exclusive highway driving, except for minor diversions for meals, bio-breaks, and hotel.
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• Round-trip fuel economy: 5.1 L/100 km = 46.1 MPG US = 55.4 MPG Imp (all actual, not indicated)
  Uphill to CO: 5.2 L/100 km = 45.2 MPG US = 54.3 MPG Imp
  Downhill to ON: 5.0 L/100 km = 47 MPG US = 56.5 MPG Imp
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• I drove 1,580 miles (one way) on less than 2 tanks of fuel (tank capacity: 75 liters, 19.8 US gallons), and I still had ample fuel in my second tank when I arrived (1/4 indicated).

I hugged the right lane, and had a reflective "CAUTION / SLOW" sign in the back window.

For those who are curious, and/or those who hate slower drivers, even though they're in the right lane and not breaking any laws, here are my stats for upset drivers:

• During the 3 days (~32 hours) of driving to Colorado, 8 drivers expresses some sort of displeasure (average 1 every 4 hours, or 1 every ~200 miles).
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• During the drive back, only 3 (average 1 every 10.6 hours, or one every ~527 miles)
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• Some of the more interesting examples of upset drivers included:
  - 3 lanes wide, nearest vehicle front or back is at least 20 seconds travel, other guy drives quickly up to my tail, tailgates me for over 15 seconds flashing his lights, passed blowing his horn. Remember, there are two absolutely empty lanes to the left, in the same direction! I guess he owned the lane I was in ;-)
  - 2 lanes wide, traffic flowing freely, no lineup behind me, leans on horn as he passes, flips the bird.
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• I was passed by numerous police officers. Pulled over by none. None indicated any problem. I drove through numerous speed traps without incident.
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• I didn't count the many thousands of drivers who passed me effortlessly, safely, and uneventfully.

BTW, I hypermile for the sheer fun of it. I love my car, and I love driving it. I do not aspire to get the best fuel economy independently of vehicle.

Truly epic journey Steve! Massive miles, and great figures. It's awesome having a long range isn't it? Kind of miss that, but then again, I don't do the mileage anyway. Do you have a dashcam? Would have been cool to do a sped up time lapse of your journey. Roughly how many miles can you do between breaks?

Draigflag: No dashcam, but I want to get a combo GPS/dashcam in the future. My road time is limited by my need for the occasional bio-break. I have an ice-chest beside me with drinks. Although I didn't keep count, my guestimate is about 4 to 5 hours continuous road time. So at 50 MPH, that translates to 200-250 miles between pit-stops.

I don't find those long drives tiring, either.

Additional Diesel Info: My car uses DEF (Diesel Exhaust Fluid, or AdBlue), and has a DPF (Diesel Particulate Filter). During a typical 800 km (500 mile) day, at some point, my car would kick into the "DPF Regeneration Cycle" once for the day.

If the DPF starts getting clogged and your driving style will not let it clean out (i.e., driving at 80 KPH (50 MPH) all day long will accumulate soot in the filter), then the car automatically drops out of 8th gear into 7th to raise the RPMs, which raises the exhaust gas temperature to burn off the particulates accumulated in the DPF. During this cycle, you cannot force the transmission into 8th gear while maintaining the same speed.

So during the DPF Regeneration Cycle, I'd raise the cruise control from 80 KPH (50 MPH) to 90 KPH (55 MPH), which would allow the car to shift back into top gear (8th) while it regenerated the filter. Driving at that speed for 30 minutes cleared out the filter, after which time I could resume driving at 80 KPH (50 MPH), optimum hypermiling speed.

(Audi A6 2011, 3.0 TDi 8-speed auto)
I've been doing similar for the past few days: I live about 4km from the highway entrance, and work 2km from the highway exit. All-in-all one way commute to work is 38km. Legal minimum is 60km/h, but I found 80km/h on the highway more efficient fuel economy wise. I was able to do a whooping 1050km on one tank @ about 5l/100km (47mpg). I was able to achieve 4.7l/100km (50mpg) on the highway only, but was increased to 5l/100 due to driving from highway exists to home/office.
This was all done during rush hour traffic, so I'm happy with the outcome. I've found 80km/h to be the most efficient speed for this vehicle. I'm guessing I have the same engine/gearbox as OP. I'm wondering if, on a trip such as OP, I'd get the same or better fuel economy.

Great figures. Do you find that a minimum highway speed limit helps keep rush hour traffic moving? Here in the UK, even the motorways come to a halt during "Crawl" hour!