High speed fuel economy
 

I took a 240 mile trip last Sunday and did it at an average speed of 80 MPH. Basically 75-85 mph as the speed limit was mostly 80 mph and conditions nice, zero stops, in about 2 hours 45 mins. The car a new 2022 Hyundai Sonata hybrid.

https://ecomodder.com/forum/member-h...310-134750.jpg

Was pretty happy with 42.5 mpg calculated at the pump, the car said I was getting 43.2. There was 1200 feet of elevation gain start to finish and there were winds of 5-15 mph but not a tail or headwind. The trip back I slowed down about 5 mph, had the downhill and similar wind and got 44.5 mpg at more like a 75 mph average while driving but stopped once along the way.

Pretty happy. What's the best 80 mph average others have gotten? Even the TDIs seem to drop off pretty hard after 75 mph. My ev mode would kick on and off even at 85 mph so that was cool.

Yeah .24 cD!

i love the rear of the sonata hybrids. the new ones look amazing. light box cavity and vortex generators. i wish the rear of my ioniq looked that way

I was just reading your thread, you were already talking these 80 mph speed limits. I'm just up from you in Montana. My only mod so far was to put the tires at 43 psi.

I did shop both the Sonata, Elantra, and Ioniq hybrids but liked them size and looks of the Sonata and the prices are all really close.

Mine is that pearl white and the accents are all black.
https://ecomodder.com/forum/member-h...310-134805.jpg

I suppose a 1.9 TDI swapped 1st gen Insight with long gearing should do insanely well at that speed.

First gen Insight gets ballpark 55mpg at that speed. In my Insight with a TSX engine (runs an 11 second quarter mile) I'm still getting around 42mpg at that speed.

Montana is my dream state to live in but it’s so expensive. By far my fave place. Especially west Montana. Bozeman. Missoula. Glacier. Flathead lake. All from like another planet. Psi and rolling resistance doesn’t matter at highway speeds I found out. Swapped my 38 psi blizzak snow tires to 45 psi ecopias and it’s the exact same mpg going over 80mph. Now City driving is completely different w though

Nice car look and pearl color. Although I prefer metallic or plain white. Because pearl is expensive to paint. Show a photo of the trunk to see if there is a small cargo opening.

I'm sitting around 125 mpg-e at 80 mph on summer tires. Snow tires kills it a little. But MPG-e is a mostly useless metric when comparing to fossil efficiencies. 46 is pretty good for a hybrid!

Can't wait to get an Aptera and be around 300 mpg-e...

125 mpg-e @ 80-mph
 

Are you taking charging losses into consideration ? And those would vary, depending on the charging infrastructure. 115-VAC vs 220-VAC etc..

I feel the best way to compare a BEV to an ICE is to figure the cost to power the vehicle say 100 miles. This also works well for unleaded vs diesel. Sure diesel often gets better mpg, but around here unleaded is 20% less cost wise. My car also is great at using the low octane unleaded.

So then with electricity rates, for a highway trip you would have to consider the fast charger higher rates although on my example, a 240 mile each direction, you might be okay on your less expensive home rates.

So in my example I was $9.30 to go 100 miles at an average of 80mph (75-85mph)
My brothers EV6 would probably cost about $10.50 to go 100 miles using Walmart fast charging and $4 to go 100 miles charging at his home

holy moly thats expensive for 100 miles. my car costs about 8 bucks to go 100 miles on the highway. and its just a basic hybrid. no plug in or ev or anything

EVs also average about 3-4 cpm less to maintain so even if you're paying high fast-charging rates the EV probably comes out ahead.

But if you value your time at minimum wage ($15 here), it costs another 1-2 cpm in time waiting to recharge vs pumping gasoline.

And then if you value the cleanliness of energy extraction, transportation, and use you probably have to give that advantage to EVs even with the nastiness involved in manufacturing batteries & burning coal.

And those costs were at 80 mph, it would be much less around town or at slower highway speeds.

expensive
 

In the context of the 'average' motorist, you're only going to do a few holiday road trips, and one 'vacation' a year.
Most charging will / can be from home.
'AOC's' BOLT is averaging over 130-mpg'e.
A one-time expense for off-peak, net metering hardware sets one up for, 5-cents/ kWh. Or $1.87/gallon-e, in April, 2022 dollars. That's 1.43-cents / mile.
Not a bad hat-trick.

That’s the main reason I couldn’t get an ev. Def not the average motorist. I drive about 50,000 miles a year and do road trips every month that clock in a few thousand miles. I can’t stop to charge every few hours of driving. Would drive me insane

not average
 

If we can check off all possible scenarios, you'll be good-to-go dialing in your hardware.
Best we make all mistakes on 'pixels' rather than with your bank account.:p

Yeah hence the aero mods for high speed driving. The car gets amazing mpg hypermiling around town. But once I hit that wide open interstate in Utah, Idaho, New Mexico and Texas, that mpg CRASHES!

wide-open-interstate
 

Yeah, you're a very good candidate for aero.
The velocity-cubed relationship is a tough task-master.

The heart-warming tail of an Ecomodderer who put a roof-top tent on his TDI New Beetle and was dismayed by the MPG hit, accepted some friendly persuasion, and achieved better than OEM mileage with a hitch-mounted rooftop tent.

ecomodder.com/forum/showthread.php/compact-camper-alternative-new-beetle-tdi-hard-mounted-26915

[explanatory pics victim of a fickle image hosting site]

You might achieve a similar result with a long, skinny hitch-mounted fiberglass pod.

My 1st gen volts would go from 45mpg @ 60mph to 32mpg @ 85mph.

Well I made another run, which will probably be an every other weekend thing now, and it was colder and windy and my mpg dropped to 36.5 mpg. The one direction I was fighing a straight 25 mph headwind and was only getting 34 then the return trip had clamer wind and I was about 40. Still not as good as the first trip.

It will be interesting to see how much it changes with the weather.

I recently found out that Car and Driver now includes a 75mph test for their fuel economy numbers. Some might find it useful.

Umm stupid question: if you force the fuel motor to start does that not include energy to recharge the battery which is reflected in the economy?

serial-hybrid engine energy vs overall MPG
 

Very good question!
1) Since the engine runs @ constant rpm, and is optimized for this specific rpm, it's likely to have one of the highest thermal efficiencies around. Perhaps 42%.
2) And since it's directly-coupled to the 3-phase alternator/ rectified generator, it has no 'powertrain' mechanical losses 'in between.'
3) The 'generator' might have a mechanical efficiency equal to the motor, @ 97%.
4) And GM's motor efficiency is right up there with Tesla and Lucid Air, around 97%.
5) If you're burning REGULAR UNLEADED, E10 gasoline, it's specific heat content is 111,836- Btus/ gallon.
6) From each gallon of gas, you'd have 46,971.12-Btus worth of energy from the engine.
7) 45,561.986-Btus from the 'generator,' into the motor. About 13.349-kWh available/gallon.

I take that answer is "YES" then.

YES
 

Exactomundo!:)

43 mpg is pretty impressive for that speed. I can see what my 1.5l Turbo (non hybrid) can make on a 60 miles trip, but I have a lot more evaluation and even though I'm driving on the Autobahn, it's hard to maintain 80 mph as average speed. Because you're getting constantly slowed down to 40 mph (construction zones, semis and slower passing vehicles) and then I have to hit very high speeds to reach an average speed of 80 mph.

I'd say my fuel consumption could be arround 35 mpg (6,8 l/100km)

TDIs (1.6, 1.9 and 2.0) would probably do 46 mpg

Did you use cruise control most of the time?

My 2.0 golf tdi does 40 mpg at 80 with the neutering software, was about 10% better originally. The way I drive it, anything above 75 means an extra fuel stop which isn't lesser time overall

I just set the cruise at 85 mph, but there are places where you have to slow down to 70 mph. The passes, the couple cities. Now that summer hits, road construction starts so averaging 80 is going to be tough.

I swapped vehicles with my girlfriends 2005 3.0 liter awd Subaru outback wagon and even slowing down 5 mph, it could only manage 22.9 mpg on the same run.

80- 93 MPH speeds average being about 87 MPH for 800km 497 miles consumption 5,6 l/100km or 43 MPG with roof box on top of the Audi A2.
https://youtu.be/BtY7zt9qR6E

Slower speeds about 90km/h avg speed 3,85 l/100km or 61MPG for 1000km
https://www.youtube.com/watch?v=kFuufxZvRLM
Setup can be seen in this video.

Man, I wish I could travel 500 miles at 93 MPH... and at that level of efficiency.

I'd have to drive 45 MPH in the Mazda CX-5 to achieve 43 MPG.

Found this post in a thread about the previous gen Hyundai Sonata Hybrid (2018), thought this would fit here:

Traffic flow here is just too bad to hit an average speed of 80 mph at daylight. When the ACC is set to 80 mph you get an average speed of only 70 mph at the end. The fuel consumption was 47 mpg (5 l/100km).

https://youtube.com/watch?v=MODJ2J5_...ature=youtu.be

Car is a The 2017 Honda Civic 1.5 Turbo with a CVT.

I was in the low 50s yesterday going 80 with cruise control. Then 11 mph kicked in and dropped me down to 48-49mpg and I got mad

I totally feel that. I usually don't drive that fast to avoid getting mad about a ruined gas mileage. And here are too many inclines, those will destroy the fuel economy if you drive too fast. So I'm normally driving at an average speed of only 55 mph.

Well I was driving 700 miles in one day across multiple states in the high desert out west. Wasn’t trying to hyper mile. On long trips, going even a few mph can save you hours…

The good thing about having an inefficient drivetrain is...higher speeds don't reduce fuel economy much XD

With my short geared, big cam V8, I get 25mpg at 60, 22mpg at 70 and 20mpg at 80. Climbing a hill takes barely more fuel than going on flat land because half the fuel goes towards heating the engine oil.

I've been thinking about adding a box cavity to the rear of cars to use less fuel on long trips though, probably doable with just cardboard (sprayed with paint or something to repel water) and cargo straps.

I just thought you were hyermiling because you mentioned 50 mpg :snail:

700 miles on one day is incredible, I once drove 700 miles relatively fast but with a pretty fuel efficient Diesel BMW.

Google Maps says this trips takes 9 hours :turtle:

https://ecomodder.com/forum/attachme...1&d=1654434547

Don’t think 80mph on cruise control is hypermiling for me lol. The headwind really messed me up though. Sometimes I have to put cruise control on 88 or 89 mph in the desert because the highway speed limit jumps to 80 or 85mph and everyone’s trying to go 90. Maintaining 90mph still drains gas, even in a hybrid with a cd of .24. Hence why I need to do more aero mods