LT Sedan vs. RS Sedan MPG drop?

[Joesonic]

My 2019 LT 1.4L AT Sedan was rated at 26mpg City/36mpg Hwy

I traded it in and got a 2020 LT 1.4L Sedan w/RS pkg. It was rated 26mpg City/34mpg Hwy.

Wondering why the highway mileage is lower, has me eyeing the RS pkg addition of the rear decklid spoiler and the increase in tire width from 195/15" to 205/16".

Has anyone done a spoiler delete? Is it really necessary for handling?

What about narrower tires? Could I go with 195/16" series rubber?

For my tastes, the LT sedan on the 15" tires handled better than an economy car should. But with the RS pkg, the car carves corners nicely! I don't need to fly around sweeping curves at 70mph to get to work and I can sacrifice a little high-speed grip for all-around better fuel economy.

 

[journeymansun]

My 2019 LT 1.4L AT Sedan was rated at 26mpg City/36mpg Hwy

I traded it in and got a 2020 LT 1.4L Sedan w/RS pkg. It was rated 26mpg City/34mpg Hwy.

Wondering why the highway mileage is lower, has me eyeing the RS pkg addition of the rear decklid spoiler and the increase in tire width from 195/15" to 205/16".

Has anyone done a spoiler delete? Is it really necessary for handling?

What about narrower tires? Could I go with 195/16" series rubber?

For my tastes, the LT sedan on the 15" tires handled better than an economy car should. But with the RS pkg, the car carves corners nicely! I don't need to fly around sweeping curves at 70mph to get to work and I can sacrifice a little high-speed grip for all-around better fuel economy.

Aspect ratio of the tires , 205/55-16 205/60/16s fit fine and would give you 2-3% reduction in rpm’s at highway speed.
17 Sonic RS 1.4 t’s been tuned and modified. Driving like an absolute granny talking 68-70 mph slow out of the hole flat terrain , no mountains etc. I’ll get 38-40 mpg but that’s trying real hard.
My normal is 26-28mpg like a bat outta hell.

 

[Joesonic]

Thanks for the response journeymansun! I was thinking going with a narrower tire for less contact patch on the road. I was looking at the 185/60R16 (same size used in the Toyota Yaris). They would only increase revolutions slightly but would be 20mm narrower and therefore weigh less and reduce rolling resistance.



Any thoughts on this? Would there be a significant loss of load carrying capacity?
(Maybe my question might be better posted in the wheel tire forum, but since I'm trying to find a simple way to increase fuel economy, I thought I'd post here first).

Also, what about that decklid spoiler? Anyone try to remove it?

Thanks for the help!