Well, I think you're comparing apples and oranges again. Your RRS 5L is supercharged, and the 5.7L in the pickup is naturally asperated. I shouldn't need to explain the difference to an engineer. the RRS's supercharged engine has 518HP. The pickup has 400HP. Forced induction has that sort of effect on a powerplant. The Rivian you have on order is electric. Again, it's an incongruent comparison. Besides, I can't walk into a dealership and actually purchase a Rivian today so until they're in mass production, it's vaporware and a moot point.
By your overly simplistic standard (displacement) your RRS 5L is kinda weak in comparison to a 5.7L Hellcat making 807 HP.
They're different vehicles, with different objectives, and different compromises. I'm sure your Rover suits your lifestyle better than a truck would. A truck simply suits mine better for various reasons. Like, hauling hay or mulch which I do pretty often. Finally, a truck is just what I LIKE to drive. Which is all that matters to me. I'm paying for it, I like it, so that's that.
Trucks also have different gearing and final drive ratios than SUV's and cars. These all effect acceleration performance.
I would be curious to know what your engineering specialty is. It doesn't sound like it's automotive or mechanical.
