Funny. I have a fiat 500 four cylinder that gets forty five MPG. The thing is I live in the city. My Fiat car computer tells me that my average speed is twenty three MPH. The Fiat actually gets twenty two MPG.
I have an old Ranger Vulcan V6 which is supposed to get maybe twenty or twenty one MPG. I get eighteen or nineteen MPG in the city. The two vehicles are so very different, but the mileage is pretty much the same.
I think you might need to take a look at how differently you drive the two, you might not even realize it.
My driving is mostly highway, not to mention my vehicles are a fair bit different, so not trying to compare to your driving.
The 1999 Ranger a was 4.0L 4x4 auto prior to V8 swap. I don't know what it was rated for, but it consistently got 15 MPG combined. I think may have picked up a couple of MPG from the swap, but still got a lot of figuring to do there and don't really care about MPG in it.
The 2000 F-250 7.3L 4x4 manual was consistently getting 19-20 MPG. That mileage with that amnount of torque on tap is something else making it hard to let go. On the flip side, it might get better mileage, but the fuel is also more expensive.
The 2010 Forte is rated at 23/31 MPG. I consistently show 28-29 MPG tank average on the built-in monitor, I have gotten it over 30 on the interstate, and I'm not friendly with the skinny pedal. The times I've checked it at the pump the monitor was accurate.
The 2021 F-150 2.3L auto 4x4, I'm showing it to averge 21 MPG. Haven't driven it on anything long distance to know what it can do. Putting it into sport mode doesn't seem to decrease the mileage much if any.
Don't even ask about the F-100, it used to be single digits. I think the Holley Sniper bumped it up to low double digits, but I don't try to track it, also don't drive it much at all. Like the swapped Ranger, don't much care about the MPG, but interested to how it might change with future mods.
Either Fiat was being overly optomistic on what they rated the 500 at, or you might be a little happier with the skinny pedal (compared to Ranger) than you may think. Just my opinion, I'm several states away, can't say how my vehicles or MPG would fair in your area. Also can't guess at how I'd do driving your vehicles and, having stood beside a Fiat 500, wouldn't want to spend enough time in one to find out.
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