Read this thread and no one pointed out one basic thing. All the new cusions/foam even matresses are hard when they are new& facepalm for people saying there CITY 56' is more comfortable then brand new city aspire or whatever. I have had a recent experience of sitting/driving in three brand new cars Wagon R 2015, Toyota Corolla 2015 & Honda city 2015 (i personally own city exis). Obviously i had the same experience sitting in corrolla and wagon r that is stiff seating just because they are new. they'll soften up with time. What the OP can do is to get 1 inch thick foam pads; cut and place them under seat covers for temporarily.
Similarly the suspension of PKDM cars are stiff because they are ZERO meter. We find JDM cars soft, comfortable and with soft suspension and comfy seats because almost all of them are USED (a Fact). drive it for a couple of years and then drive a zero meter car you'll feel your car has gone soft with time as compared to that new car.....!