I’ll admit, sometimes I’ll start to write about something with a very narrow, personal focus and wonder, what the hell am I doing? Does anyone actually give a shit? And then I try and turn the tables and think, well, would I give a shit about something like what sort of real-world gas mileage a 30-year-old carbureted 1-liter JDM car makes? And you know what? I kinda would. So, here we go: This is what sort of gas mileage my 1990 five-speed Nissan Pao gets.
I’m not normally the sort of person who regularly computes gas mileage; this is partially because I’m wildly disorganized and partially because I think the very practice of assigning one number to a car for its mpg rating is kind of absurd.
I’ve written about this before — there are so many factors that affect mpg: how you’re driving the car, the ambient temperature, the terrain, the wind, the random events and situations you may encounter while driving, fuel ratings, and so on that, really, mpg should be thought of as a range at best.
That said, I was still curious about how much gas my Pao used, mostly because the ratings I’ve seen online were so impressive, which makes me a bit skeptical.
Well, they were both confusing and impressive. I’ve seen some sources that claim it can get 51 mpg city and an insane 79 mpg highway, but if you keep reading you see that huge number was rated while driving at at steady 37 mph.
Honestly, I bet you could get almost 80 mpg out of that 987cc engine if you were hypermiling it at a steady 37 mph (I’ve done similarly miserable things), but that’s just not a reasonable test of how humans actually drive.
Those numbers seemed way too optimistic, or at least the results of testing done in absurdly ideal circumstances. Other sources also gave impressive numbers, like this one that gave 69 mpg (for 60-mode? is that highway?) and 43.2 mpg for whatever 10-15 mode is.
These look to be Japanese fuel economy cycles, with the 10-15 mode including:
... a sequence of a 15 minute warm-up at 60 km/h, idle test, 5 minute warm-up at 60 km/h, and one 15-mode segment, followed by three repetitions of 10-mode segments and one 15-mode segment.
so...that’s basically still a 37 mph-limit testing, it sounds like. The 60-mode I think is the steady 37 mph one? Either way, these still seem way too forgiving compared with how anyone would actually drive.
I saw some other numbers giving an average of about 31.2 mpg, with ranges of 31 to 37 highway, 25 to 30 city, and those seem more likely for a carbureted engine from 1990.
Luckily, it’s easy enough for me to do an honest test of real world mpg: take a picture of my odometer at one fill-up, forget I did that, then remember after a couple weeks of driving, when the tank is empty again and see how far I went.
Here’s my moody nighttime shot of the start, just post fill-up. I put 7.5 gallons in it, because even though the specs say it has a 10.6 gallon tank, I have yet to manage to ever put more than 8 gallons in it even when it’s at that last mark by the E. I just treat it like an 8 gallon tank, because I’ve never seen any evidence it can hold any more.
Okay, the mileage there is 164,326.6 kilometers—just over 102,000 miles. That noted, I then drove the car for a stretch of 17 days, and made sure to not fill it back up until the fuel gauge needle was touching that last mark by the E, just like last time.
During that fortnight-plus-three-day period, I drove it like I always do: kinda aggressively, because that’s how you have fun with a 52 HP car, but with occasional periods of calm. It was mostly city-type driving, with a couple of 30-minute-ish highway-speed level stretches, and one day with a one hour, 20 minute each way trip, for a total of about 158 miles of a mix between 70-75 mph highway and 55-65 mph back-roads driving.
That was a trip I took with my kid to Wilson, NC, to see America’s strategic reserve of whirligigs. I highly recommend it if you’re in the area.
I think this was a very honest, normal-human-driving test, a good mix of city, highway and the blurry areas in between. There were plenty of periods of hard driving as well as more relaxed driving. More important, I forgot I was planning on doing an mpg test until I actually had to go get gas, so there was no subconscious bias to try to get better results that I suspect I would have succumbed to if I remained aware I was doing a test the whole time.
So, I pulled into the gas station with the needle at that last mark, filled up with the same 7.5 gallons, and here’s how far I’d driven:
The odo says 164,761.4 kilometers. So, that’s a total of 434.8 kilometers, or 270.17 miles. If we divide that by 7.5 gallons, we get what I think is a very respectable 36.02 mpg.
That’s pretty good! Oh shit — I just remembered something. My tires are a bit bigger than stock. I’m running 175/70/R13 tires, and stock ones were 155/SR12. That’s pretty close, but the diameter is 1.04 times as big, so I guess I have to divide my 36.02 mpg by 1.04 which knocks me down to 34.6 mpg. Damn!
I could have just kept that dirty secret to myself but, well, I respect you all too damn much to lie to you.
This is certainly a far cry from the absurd 79 mpg or even the 44 mpg I saw online, but for real-world driving, over real-world terrain, in cold weather, an idiot behind the wheel, a roof rack with home-made, aero-killing wood crossbars, probably a few vacuum leaks and 30 years of driving, I feel pretty good about my almost-35 mpg combined.
Most Paos were automatics, so if you’re in the market for one and fuel economy is a big issue for you, expect a good bit less from that three-speed auto one. I’d suggest hunting down the five-speed ones anyway, as they get the most out of that little stable of 50-odd horses.
Not all old cars are gas-guzzlers. I mean, the Pao is small enough that I don’t suspect anyone thought it was, but still. Also, I’d suggest that most of you, just out of curiosity, should try doing a similar test on your cars, just to see how it actually compares to what the EPA claims.
My guess is that, even with modern, technologically-advanced, efficient cars, the real world numbers aren’t going to be as good as the window sticker. Still, better to know the truth, right?
CORRECTION: As some commenters have pointed out, the larger diameter tire means I should multiply, not divide, by 1.04 to compute the MPG. This makes sense, as the distance traveled on the larger circumference is greater than the smaller circumference, right?
So, in that case, 36.02 times 1.04 gives me a whopping 37.46 MPG! Even better!
David told me to divide, and he’s better at math. I blame him. Unless there’s some arcane way that he’s in fact doing it right, against what seems to be logic, in which case, I’ll thank him.
But I prefer 37.5 MPG, thanks.