~40.75 mpg In my Elantra
 

Finally surpassed the 40 mpg mark for my 2012 Hyundai elantra. 380 mile round trip to Mathis Texas back to Austin. I even went through downtown Austin in rush hour and still managed to keep the tank above 40. My best previous trip was ~39 mpg. I felt like I could have pulled off a higher number had I not hit 5 lights at the end of the trip. No EOC at the light because it was 90+ outside and my girlfriend mandated the use of A/C.

Possible reasons for the increase.

1. I kept the car at an average speed of about 62-63 mph.
2. I added a revised underbody pannel from the rear axel back after my last trip south.
3. I may have had a favorable tail wind on the return trip.

Grats!

Cool beans. What tire inflation pressure do you use? We drove my wife's 2012 AT Elantra to California from Louisiana. 900 miles at the speed limit got us 34.2 mpg. One 404 mile tank at 60 mph got 38.4 mpg. Then I inflated the tires to max. sidewall pressure, kept the speed @ 60 mph, and we averaged 44.7 mpg for the next 1100 miles.

I have kept my tires at 40-to 42 psi since August of last year. I didn't see much change but I know it can hurt. 44.7 is a great return. I can image that I would have done better if I could have made the whole trip at 60. I felt like I at least had to maintain 65mph durring the 75mph speed limit sections. Most of the traffic was already not happy with me since they were doing about 80mph.

On a second note my 90 day average is finally above the epa's combined number of 32mpg. I can definatley see that my changes to the car, my driving style and some route planning have made an impact on my fuel consumption over last year around this time. Limiting the use of the A/C has aslo helped a little. Although, not on this last trip.

New best tank was 42.98mpg same route as before. The only change was the addition of a front upper grill block. Then today I had a record trip of 49.5mpg on the way home from the store. I can only imagine what I could do if I could Eoc.

Why can't you EOC?

Its not good to EOC if you have an automatic transmission.

Keeping the TC locked, speed down, no stops or hills, & the AT in 6th gear, are the keys. I could probably approach 55-60 mpg on a road where I could drive @ 45-50 mph all day.

My 2013 auto Elantra real-world steady-states around 51mpg in 6th gear, about 49mpg in 5th gear & 48mpg in 4th gear, using 100% gasoline(ethanol-free). If a driver is even slightly impatient however, Elantra's low 131 lbs-feet of torque, makes mpg go away quickly, thus all the complaints about Elantra mpg giving somewhat less than EPA ratings.

Presently, my Elantra is averaging 39mpg(last 5 of 6 tanks have been 40mpg or more) with city driving being 15% & tanks used up in 4-7 plus days.

For yours, or do you just mean in general? It could be more involved, depending on how one looks at it, but depending on the drive, it could be worth it. There are some cars that it should NOT be done on, I was just curious.

I think the general consensus is that if a car with an automatic transmission can not be flat towed then you shouldn't EOC. My owners manual specifically states that the car should not be flat towed. What I've seen discussed was that EOC could potentially harm the transmission because it doesn't have the capacity to cool its self while the engine is off. This is due to no fluids being pumped through the transmission unless the engine is running.

I think I need to get around to doing a speed vs mpg chart. The Automatic transmission is a joke because with the transmission in gear its gas mileage is awful below 45mph. I officially hate torque converters. It only manages 35 maybe 40mpg below 45mph on flat ground. All the 5 to 20 mph trolling I have to do because of traffic kills my averages. I try to coast as much as I can but EOC would make a big difference in my ability to get better gas mileage. I predict I could average 45mpg tank to tank with a manual transmission without a problem.

Accord V6 Auto Manual
 

I have an Accord V6 automatic and this is what the manual says. I have taken the advice of this forum and no longer EOC.

You are probably right, look at my Mazda 3, I've hit over 50 with the manual tranny without EOC.

The other issue is that the car can not be restarted until it has come to a complete stop and is placed in park. The car has to be in park to start, the starter is disabled otherwise. I'm sure that feature could be bypassed but its not worth it.

This is not universally correct. I have an auto on my 09 Corolla and I routinely get between 42mpgUS and 44mpgUS every summer with no tricks except for driving with load up hills, just using the cruise control and going 55mph (eco mods not included). I can beat my brother any day of the week in his 5 speed Corolla if he is only utilizing the same techniques as I do due to the lower final rpms at highway cruising speed. If he starts doing EOC and other tricks he would turn the tides though.

At 45mph I can further achieve 55+mpg on flat ground using cruise easily. My car has fairly aggressive deceleration fuel cut. So your findings are somewhat an ECU/engine dependent conclusion.

I realize this is not a universal fact. It is true for my make and model. That is why I need a speed vs mpg chart for the Elantra. For me and my situation having a manual transmission would make a world of difference. When at low speed with the torque converter unlocked the Elantra gets really poor gas mileage! In the future when the warranty is no longer valid. 8 years from now. I will rig up something to lock up the torque converter. I'm almost certain I would see a big increase in efficiency. When I'm able to get off the back roads and take the highway I easily see 40+ mpg out of the car at 60mph.

Edit: After rereading your post. I realize what you are describing is basically an ideal driving scenario for an automatic. If I was able to cruse at 55mph without having to stop repeatedly for school traffic, lights, stop signs or climb hills with 18% grades (with no opportunity to coast back down), then yes I would be getting 40+ mpg on every tank.

This is my 1st time in the forum. Awesome... I bought '15 Elantra base model with auto tranny. Finally broke into 40's myself. Surprising since i commute from LA Riverside (ca) everyday while everyone else is too.

390 miles on 9.4 gallons = 41.489 mpg

You guys with the new elantras are lucky. My g/f followed me back from dallas- I was in my Ranger. She got about 1.3mpg better than I did, she was following my wake, and we were doing 55-65mph. She has an automatic. That car truly does suck for gas mileage considering what it is.

8-28-2013
Elantra update:
Love our 2013 auto Venetian Red Elantra(tho the wife, not so much) & it is still in the family, altho with another person. We then bought....another Venetian Red Elantra, 2016 manual version. Wife really loves it.....for the manual tranny & for the interior color, which she feels makes the car....smaller. ha ha ha Anyhow, the 2016 Venetian Red is nicer, with a deeper red, gleam & a trace more metallic flake(still not as sweet as other brands). Also, the 2016 engine is much quieter, at idle, than the 2013 engine. The electric steering is more precise & reacts better to slight inputs. On the new "quiet pavements" that are smooth, the 2016 Elantra is very low in road, tire noise & very very low in engine noise.....very sweet & radio listenable.

As for mpg, the 2016 is as gas stingy as the 2013, with many 40+mpg tanks. We finally got a longer trip on the 2016 Elantra(which we never quite got with the 2013), with stops at the ocean beach for pix & beach walking, hilly driving away from the ocean, & some stop&go I-5 driving, but mostly heavy traffic but steady 60mph driving. 2016 Elantra turned 46+mpg!!!

Again, all with 100% ethanol-free gasoline(E0). Both the 2013 & 2016 get 3 to 3+ fewer mpg, using E10. Because the EPA & "ethanol in gasoline industry" drove E0 to rarity, E0 is much costlier than E10. But, some places like Oklahoma & one E0 station in Aberdeen, WA (others?) sell E0 for the same price as E10.

Update again:
Both Elantras have a total, 120,000 miles with nothing wrong with either one. With another Hyundai (different model), I expect they all will cruise to 200,000 miles each, with little effort..... & our mechanic will still be unable to remember my name.

Bought a 2017 Elantra for one of my daughters to drive. Anything over 10 miles 45 mpg indicated is as easy as setting the cruise at 55. The 3 days I drove it to work 52 indicated, 49 calculated on a short tank.

Yeah, about 6% difference (I assume you used 87 octane E10). If you had used 87 octane 100% ethanol-free E0, your MPG might have been 52 indicated, 52 calculated. Our two Elantras tend to give more accurate car computer to pencil/paper results burning E0, compared to using (not burning efficiently) E10.