400 mile tank - doable, but PITA
 

I had an FRS for 3 years, never crested the 400 mile mark somehow, now about 6 months with the 86 and decided to try it out - apparently very doable, even with just daily commute. ~33.1MPG actual, 35MPG on the trip computer, tank needle flat, about 40-50 miles after the low gas light came on.

Welp, back to my normal 23MPG tanks.

Edit (commute details): Atlanta city area (all inside the perimeter), about 10 miles each way, about 80% interstate by distance, half by time, a dozen or so lights, occasional insanity like going 4 miles in 1.5 hours.

Man, I get 21 MPG bro. I'm stock everything, just aftermarket wheels kills my MPG. :cry::cry::cry:

I did a mountain run couple of months back with my old Lotus club and overestimated how nuts they were. We ended up doing over 200 miles in one day, all at pretty much WOT, so when I realized I'm almost empty, I was good 80 miles from nearest Costco.

Decided to try to limp it back to civilization, and apparently we have good 2.5 gallons after the light comes on, maybe more. Assuming 13.2gal tank capacity is not a lie, I can burn through 2 gallons of gas after the light comes on and still fill up with ~12gal.

When the needle is going flat it does get scary for a bit, though.

In my 108,000 miles and 319 fill-ups I've had 3 tanks over 400 miles (most was 413 miles) and probably another dozen that could have been (were within 10 miles or less when I filled up).

Since most of my driving is commuter miles, but at near highway speeds, it's pretty easy to do. On the 413 mile one it took 11.743 gallons to fill up and was a road trip so at the mileage I was getting, 35MPG) I could have gotten to about 465 miles before running out of gas.

The after market wheels are not to blame. Mileage is based far more on how the car is driven than any parts added. Stop and go traffic and frequent WOT will chew up gas not an extra 20 pounds or so from some wheels.

Damn it TCoat, you might be onto something....

When I first got my car (had aftermarket wheels on them right from the start) I typically avg around 23-25mpg.

Now since I started shifting at higher RPM (around 4-6k now), I'm getting around 21 MPG. :mad0259:

I have never avg at least 25+ MPG in my life on this car, so I'm jealous to those getting around 30+ MPG all the time.. :cry:

Do we see a pattern here?

I find it odd when people say things like: "Now since I started shifting at higher RPM".

Does this mean you always now shift at higher RPMs? Or does it mean you used to always shift below 4k and now venture above 4k more often?

The later I can understand, but shifting at high RPM for the sake of it is retarded. Sure if you only have open road in front of you all the time and you want to nail it up through the gears... but what do you do about 3rd? 6k is above the speed limit in 3rd isn't it? Do you just stay in 3rd and cruise at 5k rpm?

If you are behind a slowly accelerating car and cannot overtake it, do you slowly rise through 3, 4, 5, 6k rpm with only a fraction of the throttle applied? That's dumb and a waste of engine wear and gas.

To drive a manual properly you need to understand choosing your gears correctly. The general idea is:

Use the highest gear that will give you the torque you require without labouring the engine.

So to nail it up to the speed limit, take it to 7.4k and use ALL the torque in 1st and 2nd, then short shift to 6th and cruise... 6th at 60mph will provide perfectly adequate torque to cruise (large hills may require a downshift, as you will need more torque).

But in normal traffic with lesser cars, if you don't need max torque, shift earlier.

i average about 643 km (400 miles) every tank lol. im sitting at 6.0l/100km (39 mpg)

Honestly, I never expected to get the gas mileage I do out of the FR-S (lifetime 33MPG). I don't drive it in any way that would be considered conservatively, but I've only averaged below 30MPG per tank 7 out of over 300 fill-ups. The absolute worst was 27.6 and that was on a road trip where I spent a couple of hours stuck in stop and go traffic (probably averaging 2 to 5 miles an hour).

Although it is not all that accurate I use the readout to see if my mileage goes up or down. The average has remained on 33MPG for the last 2 1/2 years. It hasn't wavered a single digit.

of course driving dynamics and types of travel are going to have the biggest impact, but wheels and tires make a noticeable difference as well, and its not just because of weight. larger wheels generally = larger tires with more drag. if you are like me you couldn't wait to get the skinny, efficient prius tires off and put on fatter, stickier tires like MPSS. tires with greater traction are also going to impact your mileage (think about under-inflated vs. over inflated tires)


That said i am averaging 28.5mpg according to the trip computer with 18x8 wheels and sticky 225/40/18s.

Yep. But they will have a minor impact where the type of driving has a major one.
Drive the car with the bigger fatter car like it is a Prius and you will still get good mileage (be boring as hell though).

Ya, but your gallons are bigger ...... :popcorn:


humfrz

And I bet if you went out to a flat smooth windless road and put it in 6th gear at 60 mph you'd get 32+ mpg, and if you drove across San Francisco uphill in rush hour traffic you'd be lucky to get 19 mpg.

you guys are getting 400 miles ive only ever cracked 400km (250 miles) once and on this current tank

i dont understand, doesnt 6.0l/km convert to 39 mpg? i dont see the difference so please teach me master :bow::bow:

It gets confusing.
6 l/100km = 39 mpg US gallons (the size gallon that the US use)
6 l/100km = 47 mpg Imperial gallons (the size gallon we use)


Not only do they not use metric there they change the size of the Imperial measurements that the rest of the world uses.

damn you americans lol :mad0260::thumbdown: but i guess ive been cooped up in my igloo far too long and not paying enough attention aha:iono:. too bad i didnt have a teacher like you Tcoat aha i would have been much better off lol

No you are just too young to have experienced the chaos that was the transition from Imperial to metric measurements here. The US variation on the gallon threw a monkey wrench into everything. Now pretty much any time somebody refers to a gallon they mean the US one. Hum was just yanking your chain.

I was jest ah messen wich ya ....... :D


:slap: ........ that's fer not giving me credit fer knowing how to convert from things to stuff ...... :sigh:

You see ...... I got this book ...... and in the back of it are all these numbers in lines of boxes, that if you follow the lines across and down ....... it gives you a number.......:thumbsup:

BINGO! ....... did I win .......??

(oh, that's another forum ...... the one with large print ...... :happyanim:)

humfrz - another slow day in Puyallup ....... whoops, I smell a poopie diaper ....mrs humfrz is always in the shower when the baby poops .......gotta go ....... :barf:

Yep, I remember a few years back, when the US was contemplating converting to the metric system. I was all for that, because at the time, I was working in a scientific field, where the ONLY unit of measurement was metric.

However, I reckon the average American couldn't quite grasp the concept of a logical system of measurement ....... so, the idea was dropped ...... :sigh:


humfrz

The Canadians were no better but we pulled it off.

Fixed it for you.

Normal 23 mpg commutes? How do you get such bad fuel economy on an 80% highway commute? Are you cruising at triple digit speeds ? lol.

I average 31 mpg not even trying if i work early and leave early (beating rush hour) and 30 if the traffic is terrible. 90% highway but i cross a bridge and it can be crappy if i work during rush hour.

This is with cruising at 75-80... redlining it once or twice a day when I can (dont often have room enough). The previous owner had averaged 24 mpg according to my trip odometer (reset after i changed oil) so they must have had a lot of stop and go and beat the crap out of the car!

If im just in chill mode i will be out of first at 10 mph and in 5th by 40 mph (if perfectly flat the car can manage that in 6th ok). Traffic sometimes kills your "need for speed" so to speak.

I think if you cruise at 65 you could easily crack 35 mpg.

Right when the light comes on in our cars we have somewhere between 2-3 gallons left in the tank. I've run it like 50 miles with the fuel light, rolled into a gas station, and only put 12ish gallons in it or so.

I'm at 9.9L/100km... :burnrubber: :D

Most I've ever been able to do is 31MPG once... my average is 21.9MPG with 75% city driving in the cars lifetime per fuelly...

Most I've gotten out of a tank is 334 miles, filling it up 11.78 gallons

I managed 340 before chickening out and filling up. The total that day was 374 which I probably would have made on the tank without filling up, but didn't want to risk it.

400 would be tough, would need to be 95% highway / motorway.

Not as tough as you might think, just nerve-racking but definitely not stop and go traffic.

Based on my usage, I look at 300 tank refills. Assuming that 13.2 US gallons is the usable fuel in the tank, I calculated the remaining miles to empty for each tank based on its MPG calculation.

Out of those, 186 would have been over 400 miles before empty, the max being 483 miles, most well over 400. The minimum was 383.

About 80% of these are from my standard commute (40.1 miles one way, usually takes me about 60 minutes, so avg about 40MPH but divided at about 80% at 55MPH and 20% at 0 to 35MPH).

I drive 682-720 miles a week. This is 98% highway with cruise set at 75MPH. I fill up once a week one week and then twice in the following week (just how the numbers work out I guess). I have never paid attention to how many miles I get out of a tank but would guess that I easily get 400 on a regular basis since I usually let the tank get almost empy. I will have to watch over the next few weeks and confirm or retract this statement.

I drive 682-720 miles a week. This is 98% highway with cruise set at 75MPH. I fill up once a week one week and then twice in the following week (just how the numbers work out I guess). I have never paid attention to how many miles I get out of a tank but would guess that I easily get 400 on a regular basis since I usually let the tank get almost empy. I will have to watch over the next few weeks and confirm or retract this statement.

I think I usually get between 250 and 280 a tank, but a lot (most) of my day-to-day mileage is stop and go traffic commuting.

On long road trips I regularly see 320 or higher. Usually those are starting after a tank with a few days commuting on it though.

On "usable" fuel. Does anyone know the amount of "tank" fuel the GT86 has? "Tank" fuel being fuel that cannot be pumped and is fuel for the tank itself effectively? (I take the term from aviation).

The 2017 has a "Miles to go" before empty and I determined it zeros out at around ~5 litres (1 UK gallon) remaining. However I doubt all of that could be pumped, so when it says zero... how far will it really go? Another 20? 30? miles?

Out of interest, over here, running out of fuel on the motorway is a traffic offense. You can actually be done for running out of fuel on the motorway as it's fairly dangerous for you to suddenly decelerate without brake lights. Fine on other roads, but the motorways have special laws.

Our consumption computer is a giant liar, btw. I record/reset every tank and math it, along with keeping track of the delta between actual and displayed MPG. My FR-S averaged 1MPG higher display than actual for 100-ish fill-ups, 86 so far is .8MPG higher on average, with some tanks being +1.8. I fill up at the same station 90% of the time.

Also, the more I baby the car, the more egregious the lie (my "35MPG" displayed results in 33.1 actual, while 25MPG displayed is 24.5-ish). Lies :)

Check your speedo calibration. Often the MPG reads high because the speed and thus the distance reads high.

Nah, speedo is fine, matches GPS value pretty well.

It's horrible at measuring amount of injected fuel when I'm in 6th gear going 30mph it seems.

Don't think that a difference of less than 10% is a "massive" lie but yes the computer will not agree with what you calculate. It is taking a real time averages at all times where manual calculations do not account for such things as sitting in traffic for long periods.

I think another contributing factor is the computer tops out on MPG at some point (don't remember what it is but I have noticed it). Basically, it will only give you "credit" for so much.

That's a tough one. From what I've read in the past most (but not all) auto manufacturers list it based on useable fuel but it is an average calculation and can vary by as much as 3% between cars of the same model due to manufacturing "sloppiness" in the tank. Probably more common in metal tanks than non-metal ones.