The large sand cars have v8 engine mounted on the rear of the car with a transmission attached in front of the engine.  This makes it very rear heavy with all the weight behind the rear axles,  which then requires steering brakes to turn it when accelerating.  The steering brakes only work with single wheel drive,  so they can't use limited slip differentials to greatly increases rapid takeoff traction and reduce getting stuck.

The side by sides engines have up to 150 hp with 100 lbs of torque.  They weight about 1500 lbs and some have four wheel drive.  The drivetrain which was developed for snowmobiles that weigh less than 1000 lbs,  has a belt which is suffering from so much more weight and hp.  Yamaha has switched to all gear drive and we expect others to follow.  Their three cylinder engines have reached their hp and torque maximums.  The whole engine and drivetrain will face a major upgrade as they search for more clearance,  a smoother ride and more speed.

Kleerit developed and tested this off road sport car demo model for three years.
Honda 2.4 liter engine mounted transverse on the rear of the car to maximize traction and keep good steering.
Six speed close ratio dog box transmission with a 6.30 final drive and limited slip differential. Currently testing a four speed transmission.
417 hp and 360 pounds of torque.
Weighs just under 2000 pounds.  
Top speed is 120 mph.
Goes over 100 mph in the quarter mile on sand.
Our torque to weight ratio runs well against large sand cars that weight 4000 lbs with 1000 lbs of torque.
22” of travel at the front wheels and 18” travel at the rear wheels.

This Kleerit model would make a good high performance model.
It has a 5.5 lbs of weight to 1 lb of torque ratio.

Most people that ride in the dunes are recreational drivers that don’t need that real high performance.
The goal is about 8 lbs of weight to 1 lb of torque ratio.
Weight goal 1600 lbs and 200 lbs of torque.
Reducing weight is important for: cost reduction, quicker maneuverability, getting unstuck, less frame and drive train stress, less shock needed, less expensive torque to weight ratio.