Reminds me of the Vacuum cleaner car that Chapparel used on some of their competition cars.
Yeah, that was an active evolution of passive ground effect side skirts (not that it matters much, but it was also the Brabham). I could imagine the thruster solution on the roadster actually being used to create virtual sideskirts. Then, assuming there's some air compressor on board to refill the thruster 'propellant', that could suck from under the car similar to the 'fan car'.
I could also see the thrusters being used in other aerodynamic configurations, not dissimilar to how formula one cars routed their exhausts [a few years ago] to facilitate better airflow under the rear wing. The thruster plume would effectively change the aerodynamic shape of the vehicle, and one can imagine the benefits of a dynamically sized bulge here or there, closing off or opening up a vent, etc...its sort of the evolution of active aerodynamic surfaces/features.
Last, and probably least clever, one could imagine a thruster improving downforce, which of course will improve acceleration, cornering, and [when turned off or re-directed] top speed.
I find it hard to imagine a thruster being used directly to control a car, as I find it hard to reconcile the forces required. Presumably a ~3000lb roaster in a 1g turn is reacting with 3000lb of side load across the four tires. In my brain you'd want at least many hundreds of pounds of thrust on each corner to be effective.