I had a five hour drive each way for my install, so I took readings for the same stretches of road at 70mph. I kept everything the same - phone placement, minimal traffic, no music, climate control, cruise control, etc
I took four readings at various points. I found a difference of roughly 4–5 dB on average, 71.6 dB before install and 76.2 dB after. This is typically enough for the human ear to notice. In general, differences of about 3 dB or more are generally audible, so a 4–5 dB gap would certainly be perceived as “noticeably louder.”
It’s a platform camper installed on a 2024 Tacoma Trailhunter. Between this and a 2.6 mpg drop from 20 to 17.4mpg, I’m going to research fairing options to see if I can recover some.
Nowhere near as scientific as you, but I have noticed zero wind noise from my camper. My sample size is too small to evaluate mpg, but it doesn’t seem I’ve lost much. I drive a 2020 Chevy Colorado with the V6. Over the 4+ years I’ve owned it my overall average is around 17.8 mpg
Yeah, I did that because I didn’t want to leave it to my gut. There’s one possibility that even though I used the same stretches of road both directions, I tried to make sure they were level but it was dark both ways.
I definitely wasn’t expecting that much of a mpg hit. Hopefully there’s a good fairing option I can find on here.
I have no scientific comparison data, because I had installed the Sherpa Animas rack on my 2022 Tacoma before the GFC, but it ‘looks’ like it might help. I also have a 83l Roam case mounted on the rack and both together look like they would make for a more streamlined wind flow. Look forward to what you find and some actual data.
I’ve tried a couple different fairing setups. The larger custom one on my build thread has held up well and seems to reduce the road nose and offer a tiny bump in mpg (maybe 0.5mpg), although it’s hard to quantify considering all the variables that affect gas mileage: winds, elevation, temps, humidity, octane, vehicle weight, other traffic, etc.
Headwind/tailwind could be enough difference to amount for 50 to 75% of the differences you’re seeing both in noise and mpg.
Having my GFC on a Tacoma for 36k miles, and always driving the same roads, I noticed a difference in noise level, but the mpg difference is around 1-1.5mpg. YMMV. 2016 Tacoma Sport DC with manual transmission and 4.30 gears. Nearly stock size tires.
Yup, very true! Tough to isolate for all variables without a wind tunnel. I have 5,000 miles of mpg data so I should be able to get a better idea how it’s panning out.
94 toyota pickup. about 1.5mpg impact over long runs when freeway driving. I measured this 4 or 5 different trips and then stopped paying attention.
Something important to remember is that drag is proportional to the square of the speed. So the faster you go the worse it gets. If you feel like going deeper it might be informative to do a test at lower speeds too.