Kia Soul Fuel Efficiency on ECO Mode

My 2015 Kia Soul has an "eco mode", which supposedly "helps the models to achieve a higher level of fuel economy by adjusting the engine and transaxle operating parameters". I usually have left it on since I drive quite a bit, with a 47-mile one way commute (94 miles round trip daily). Thing is, I have had no idea whether it actually does anything. It certainly makes changing gears slower, which makes it way harder to accelerate and sometimes feels like I'm driving a golf cart. Which certainly isn't ideal when I'm predominately driving on highways.

So over the past 3 months, I've started tracking splits of my mileage, gas fill ups, etc based on whether I have the "eco" button ON or OFF. Over a full timetable of 7,685 miles driven over 20 fill ups since 9/17/18, I've experienced the following performance per fill up:

Eco	Miles Driven	Gal	MPG	Count
ON	348.0	12.31	28.28	10
OFF	351.1	12.65	27.77	10
Total	349.6	12.48	28.02	20

So the eco mode actually does have an effect! My fuel efficiency is about 0.51 miles per gallon better when I have eco mode turned on. 

The car also gives an "estimated" range every time I fill it up, and these "estimates" certainly don't reflect what my tracking has shown me, skewing high in both cases and also a much smaller predicated delta between ON/OFF (0.18 miles per gallon):

Eco	Est Range	Gal	Est MPG	Count
ON	354.1	12.31	28.77	10
OFF	361.6	12.65	28.59	10
Total	357.8	12.48	28.68	20

So how much am I actually saving? Is it worth feeling like I need to start pedaling like Fred Flintstone in order to squeeze out another 0.51 miles per gallon? The current average gas price in Miami is around $2.35 per gallon, but over the course of my tracking I've been spending closer to $2.64 per gallon. So my savings would be:

0.51 miles per gallon * $2.64 per gallon * 1.56 savings per week = $2.10 per week

Is it worth ~$2 a week, or ~$104 a year, for a worse driving experience? Considering that I'm driving almost 100 miles round trip each day, 5 days a week, I think I'll leave eco mode OFF going forward.