IMO the most advanced Race UTV has not been seen in public yet, but it is the RedLands / Motive Engineering car. This car is very thought out and is very out of the box thinking compared to what you see out there right now. There are custom parts so deep in this car that most will never see or know about.
The other two cars that are racing and come to mind are the GlazzKraft car, and the Jimco. The GlazzKraft car is all 100% custom and does not use off-the shelf or modified off the shelf suspension components. They are also using a lot of carbon fiber parts. The Jimco while not the lightest car, and it using a off the shelf suspension kit, the chassis design is by far the best in strength & design. You wont find dead end tubes on this chassis. This chassis was also built to take a nerf or hard hit. Jimco does not want their customers to be a casualty, as many would be in some of the other chassis we see out there.
And I agree with Johnny, most don't look past the body work or some tubes to see what is really going on under there. Roberto Balderama 1090 car while the chassis looks funky, there is way more going on under all that. Just look at the wheels and lug pattern and you will see he is doing things way different.
But also many times these radical builds don't have success and are changed, or were just ahead of there time and come back out later in a refined design which then becomes the best latest & greatest part.