I love my 2015 EX. I got it with 400 miles in 2017 and now I have 110,000 miles on it. Driving around town it’s not such a big deal but when I drive that car for more than three hours the driver seat seems like I’m sitting on a rock.

any recommendation for a cushion that may offer both support on my butt and my lumbar?

 

I've noticed the same thing in the past, and noted that it usually hits around the three and a half to four hour mark for me.

-Easiest/cheapest fix for the lumbar is an empty plastic water bottle behind you. Simple but effective.
-Maybe a folded up beach towel for the seat.
I'm trying to think of something easy and on hand.
I haven't been driving as much lately, so it hasn't been an issue.

Maybe look at the BackJoy on Amazon. It is supposed to help with both. I've yet to purchase one though. Slips the mind when actually ordering something else.
I used to work in a tire shop and I would come across them in a vehicle every now and then. For the sake of trying it out, I'd sit on it, and it would be good for the five minutes that I was in the vehicle.
Hope that helps.

 

Check out this thread and consider removing the “back support” it makes you feel like you’re sitting down in the seat and not perched on top of it.