I've wondered about just how well an HD trike can do on fuel mileage if you get caught on a long stretch of highway between gas stations and need to conserve gas. So today, I did a 85.5 km = 53 mile test run to find out.

Now before I get anyone too excited about what I found, I should point out a few things about my trike that potentially have some bearing on the results I got today:

- My trike is a 2023 RG3 that was brand new from the HD dealer just a few weeks ago, and it had only 1238 km = 768 miles on its odometer at the start of the test.

- It has the Stage 1 hardware and tune, plus an HD Bluetooth tuner "Smart Tune" that optimized the tune to my specific engine. I have no idea if that affected MPG, but it did improve engine smoothness and power.

- The ambient conditions were 22 degrees C = 72 degrees F

- I had a tailwind going out and then a headwind coming back, with the wind averaging 25 kph = 16 mph and gusting to 43 kph = 27 mph. So, easy cruising on the way out, and fighting a headwind on the way back. A reasonably fair test.

- The entire test was done at 80 kph = 50 mph = 2073 engine rpm (presuming that if you are trying to get to a gas station before running dry, you are going to be running at a lower speed, not a high speed.

- Interestingly, at this low highway speed and engine rpm, the engine oil (the oil, NOT the cylinder head) never got above 204 degrees F.

On my 2023 Breakout 117, with Stage1 and a Smart tune, when I did similar tests, adding a "micro" windshield that had a total surface area of about one square foot (to deflect headwinds around and over me), I found that the best speed for best fuel mileage was 90 kph = 55 mph, at an engine rpm of 1976. At 55 mph, the Breakout consistently (not just once or twice) delivered a solid 55 MPG after correcting for speedometer error. Going slower at 80 kph = 50 mph did NOT improve the MPG because the Breakout gearing had the engine at only 1800 rpm at 50 mph, and that was right near the bottom of the usable torque curve. The engine was happier, and more efficient, at 55 mph.

I knew that the Road Glide 3 trike was going to deliver notably worse MPG than the Breakout because:
- It weighs 477 lb more than the Breakout
- It has WAY more frontal surface area than the breakout, due to the Road glide fairing and those wide rear fenders
- It has 15.4% stiffer gearing, running 2487 rpm at 60 mph versus the Breakout's 2156 rpm at 60 mph, so 15.4% more rpm at any given road speed.

HD says on their Canadian website that the RG3 fuel mileage on HD's standard test (whatever THAT is) is 5.5 L / 100km which is 42.8 MPG. That is about 91% of the 47 MPG that HD claims for the Breakout.

So, I hoped that I might see 91% of the 55 MPG I got on the Breakout 117, so 0.91 x 55 = 50 MPG on the trike IF I could find the correct "best for fuel mileage" speed.

I figured that no one would want to run slower than 50 mph on any highway, even if they were low on fuel, since anything slower, on a 2-lane highway, would be dangerous.

So, I tried the 80 kph = 50 mph sped for this test. I did the test on a 4-lane divided highway where I could maintain an absolutely steady cruise-controlled 80 kph = 50 mph, and all other vehicles could simply pass me in the left lane.

The results were not quite as good as I had hoped for, but not far off what I had hoped for:

In an actual 85.5 km = 53 miles, with 80 km = 50 miles ebing at the 80 kph and the remaining 5.5. km being the city street route to and from the highway, from the pump at the gas station and returning to the same pump the my RG3 used 4.98 liters, so averaged 47.2 Miles / US Gallon.

To back up the accuracy of the test, the "Range" shown immediately after the refill of gas was 466 km = 289 miles, which with a 6 gallon tank, means 48.2 MPG. That's only a difference of 1 MPG = 2%, so any error in either the fill-up or the Range calculation done by the computer is clearly small.

It is POSSIBLE I could have done better by going even slower, but like I said earlier, I think that would be unsafe on most highways unless there is almost NO traffic that you would be impeding, which would get drivers angry, and being the smallest vehicle on the road with angry drivers is a bad idea. Going faster would not produce better mileage simply because the stiffer gearing of the trike, and the resulting higher engine rpm, would work against you.

Keep in mind too that these results were with my 2023 RG3 with Stage 1 and Smart Tune. If your trike is heavier than mine (e.g. a TriGlide) or is not as precisely tuned OR BETTER tuned, your mileage may vary!!

And, do NOT expect 47 or 48 MPG when traveling at more normal highway speeds! Or with luggage and a passenger!

So, if you find yourself on an RG3 with Stage 1 and a Smart Tune sweating the distance to the next gas station, just slow down to 50 mph and you can probably get 47 or 48 MPG. Hopefully that will get you there before you run out of fuel.

Jim G

 

Man, you need to wring some enjoyment out of that machine, nut just data!

 

I believe that would be 40.15 MPG.. 53 miles/1.32 gallons

 

I enjoy seeing how I can optimize, or at least improve, the toys I buy. I am really enjoying everything about the chariot, except the drop in fuel mileage from my Breakout. In regular riding, (not tests like this), I am getting only about 39 to 41 MPG. That's a big reduction from the Breakout 117, where with my improvements, I was always in the 50s, despite the Breakout being such a hotrod in comparison. So, the chariot is a challenge, and I like challenges.

More miles on the odometer might help with the MPG, although the MPG others are posting on the forum says maybe not.

Changing to the 100% synthetic oil might also make a small difference (and will certainly provide longer oil life).

I had the OEM seat on it today, and noticed now that I get more wind pressure on my helmet than I did with the 2-up Reach seat I recently bought used from a guy who needed a TALL seat instead. The Reach seat moved me almost one inch down and also 1.5" forward. That downward and forward move was enough to reduce the wind hitting my helmet. I was able to lift my hand higher in front of my helmet before it felt wind pressure. I wonder if I might notice a small MPG increase when running the Reach seat.

Jim G

 

No, I stated that last sentence incorrectly (got sloppy). The trike actually used 4.62 liters for the entire trip of 85.5 km, which is 4.98 L /100km (Liters per HUNDRED kilometers is the way Canada measure MPG). The Canadian 4.98 L /100km translates to 47.2 MPG in The U.S. way of calculating mileage. The Range prediction comes out just a bit better: 2% better, comfirming the accuracy.

Jim G

 

A "tad" over 37 MPG's is the best that I've ever gotten on my '18 Tri-Glide (Stage I Kit).
And that's when I keep the the engine between 2500-2800 RPM's.

 

That's actually decent mileage, since 2600 to 2800 rpm is a true 60 to 68 mph. But it's 20% to 36% faster than 50 mph (the speed I did my test at), and power required with these trikes goes up with the CUBE of the speed.

I've seen other forum trike members quote MPG as lows as the high 20s. I can see that occurring with speeds in the 75, 80, or faster mph, and luggage and a passenger.

The M8 engines seem to do very well at moderate engine rpm (2000 rpm), but not so great at 2500 or 3000 rpm. Unfortunately, the weight and forward facing surface area of the trikes exact a toll.

Consider what a rider on a long tour might face. If he rides at 50 mph, he can (it seems) hit 48 mpg. But then in an 8-hour riding day (which is plenty for most riders) he can only cover 50 x 8 = 400 miles, EVEN if he makes NO stops, which is impossible for gasoline and bathroom needs. So maybe he can actually "ride" for 7 hours in the 8 total hours, so will cover only 350 miles. At say $3.30 / gallon, he's used 350/48 = 7.3 gallons and spent $24.

If he rides at the other extreme, at 75 mph, he covers 7 x 75 = 525 miles, but gets say 33 mpg (might be optimistically high, but . . .), so uses 15.9 gallons and spends $53 on gas.

Maybe he can justify that because he needs fewer hotel or camping night costs, and fewer meals, to get where he is going. But on the other hand, if he enjoys riding, and enjoys watching the scenery, maybe he doesn't WANT to REDUCE the riding time.

Me, I put on most of my miles on 50 to 200 mile day rides. Our Canadian premium 94 octane gasoline costs $1.76 / liter right now, which is $6.69 in Canadian dollars. So,At 55 mph, those would cost me $7 to $28. At 75 mph (which would be illegal where I live), they would cost me $11 to $41. I can justify the $7 to $28 for an hour or 4 of fun, and the $11, but would balk at the $41 for the reduced fun time of only 2 hours and 40 minutes.

If I were traveling a long distance, say a 3000 mile round trip, 55 mph costs me $418 and 75 mph costs me $608. So, I can get 36% higher speed, but it would cost me 45% more to get it, if I WANT it or NEED it. Food for thought.

Jim G

 

Going back to the original point of the mileage test: If you are running low on gas, you can get almost 50% further before running out, IF you ride at 50 mph instead of 75 mph.

Jim G

 

Your calculations are still off. With the data you provided, it shows 43.55 miles per gallon US.

What you are providing is a little too ambitious with regards to MPG.

It is great that you like to collect data and write about it; however, it is disingenuous to provide data that is not factual.

Proper calculations for US MPG:
4.62 liters = 1.22 gallons US
85.5 kilometers = 53.13 miles US

53.13 miles divided by 1.22 gallons = 43.55 US miles per gallon which is close to what I would expect with a lighter GR3 while driving 50 MPH US.

Typical MPG on my Tri-Glide is 34 - 36 MPG running 70 MPH on the interstate using cruse control. If I run back roads and keep the speed down around 40 - 50 MPH I can get 36 - 40 MPG (provided for comparison and your use).

 

Coolbreeze, you are correct about the wrong way I STILL stated my results, but it turns out that my actual reported MPG was exactly what I said. Here's the proof:

This is the actual gas station receipt:



You can see my transcirption error: The amount of gas used was 4.26, not 4.62, liters.

So, here is ALL the actual, correct math:

4.26 liters per 85.5 km = 4.98 Liters per 100 km.

The online converter for converting L / 100km to miles ' US gallon says that 4.98 L / 100km = 47.2 miles / US gallon.

The range indicated by the trike's computer was 466 km, which = 466 x 0.62 = 289 miles.

The fuel tank hold 6 gallons.

So, the trike's Range caclulaiton says the MPG = 289 miles / 6 gallons = 48.2 MPG.

2% difference between the actual gasoline used during the 85.5 km actually ridden and the computer's range prediction with the refilled tank.

I apologize for the sloppy transcription last evening. I must have been more tired than I thought. I normally, after each gas fill-up, just plug the liters bought, the kilometers traveled, and the indicated Range, into an Excel worksheet, and it does all the math flawlessly. It is when I try to transcribe the data into a positng, that I can make a transcription mistake (like I did above). The Excel worksheet cannot make such an error. So, the end result information I provided was not "disengenuous". My transcription was just sloppy.

Your own MPG data is about what I would expect - even for the riding the backroads at moderate speeds. When you ride backroads, at 40 to 50 mph:
- You have lots of stops and accelerations, as you change from one road top another, and slow down for curves but speed up for straights
- You are generally unable to use cruise control
- You can't GET into 6th gear, let alone stay there, since the minimum usable speed with 6th with trike gearing is about the 50 mph (about 2075 rpm) I was maintaining. Any less than that and you are lugging the engine. And you can only maintain that low rpm by nOT decelerating and reaccelerating, which is pretty hard to avoid on backroads.

I have a favorite backroads route I run often, that is about 76 km, run mostly at 50 mph, but that includes numerous speed reductions for localized speed limits (as low as 60 kph = 36 mph) and some sharper bends in the higher speed limited areas that require slowing down (deviations around farms, rivers, and irrigation canals). We also get winds here "most" of the time (2nd windiest area in Canada). I generally seem to get only about 39 to 41 mpg on those runs.

To get the 47 - 48 mpg I got on this test run, I deliberately simulated an attempt to get as good gas mileage as I could, by using cruise control, set to a modest but safe highway speed, on a highway that goes through the kind of rolling prairie hills common to our area, on a divided highway that allowed other vehicles to pass me without irritating them, made sure I ran with the wind and then against the wind, and picked a day where the wind speed was high enough and gusty enough to represent "reality". I THINK that if the wind had been lower and less gusty, I could have beat the 47 to 48 mpg, but that's a test for a future date.

Note also that HD's mileage testing must be at least somewhat "realistic". They claim 5.5 liters / 100 km, which is 42.8 miles / US gallon, for the RG3 trike. You, me, and numerous others have posted about getting 41 mpg in actual road use, so their 42.8 is close enough to say that it can likely be done by a rider consciously paying attention to getting good mileage on a divided highway at a speed higher than my 50 mph test speed.

Interestingly, HD claims the same 5.5 liters / 100 km for the Freewheeler, but 5.6 liters / 100 km for the TriGlide. So, the TriGlide's extra weight and the tour pak on top of the trunk, do not apaprently penalize the TriGlide more than 1.8% in a controlled HD test protocol. And, apparently per HD, the RG3's sharknose fairing does NOT give it a MPG advantage over the Freewheeler?? That seems odd. Maybe the HD MPG testing is done at a low enough speed where the fairing does not make enough difference to see?

Jim G