If you want to. Eco is meant to save fuel, but you’re not really saving much fuel at 82 mph. Some eco modes change the throttle map to be more linear so it’s easier to hold a steady speed. In that case, eco mode might be helpful to you.

I know it’s a ton of fun to drive fast, but vehicles tend to use much more fuel while driving at 82 mph than they do at 55 mph. This is due to aerodynamics of the vehicle and gearing. You’re probably better off just using cruise control and slowing down a bit if your goal is to save fuel. Even if the speed limit is 80, you’ll be able to go much farther on a tank of gas if you slow down just 10 mph.

Sounds like your battery percentage. Your owner’s manual will be able to tell you for sure. If you no longer have your owner’s manual, you should be able to get it from Toyota for free. Do a web search for “Toyota fielder owner’s manual”.

I have a different question regarding the dash lights on a Toyota fielder hybrid.
I understand what Ev-mode is but there is a EV light with a percentage beside it. Do you know what this percentage is for?

It is supposed to help with fuel economy, yes.

Usually ECO is a mode you can select for better fuel economy. You should be able to find an owner’s manual for your car online, and that will tell you what it means.