"The car has two engines: the production gasoline engine in the front driving the front wheels and the jet engine in the back."
Careful wording to give the impression that the drive shaft of the helicopter turbine would be connected to the rear wheels, without actually claiming that it is. So it's a car with a large flame thrower in the back, minor The Boring Company vibes.
Well possible that the author might have had more fun writing than building/driving. (I do love the incredulous tone of "#1 Does this mean I’m the right hands?")
It produces thrust in the normal way a jet engine aircraft does... with high exhaust velocity. From the videos you can see shock diamonds, so it is producing supersonic exhaust.
Any turboshaft engine is a jet engine if you don't connect anything to the shaft and point the exhaust in the right direction. Just not a very good one, at zero bypass.
If you think there is anything done in this project to increase performance you are missing the point of the joke: woah, jet engine! Woah, rated 1350 horse power! Heh, retro novelty compact with a truly glorious amount of hot air.
Will the turbine exhaust noticeable push the car? Sure. Even a piston engine exhaust does, e.g. some versions of the Merlin engine claim extra 70 HP from exhaust thrust.
Is the author having great fun (and readers who get it) by brandishing the rated rotary power of the turbine over and over again, while carefully avoiding any mention of actual performance of the car? Absolutely. But it's not mean deception, it's friendly trolling. Which is basically the essence of the entire hot rod idea. I dislike the waste (of a good car, and the occasional kerosene burn, the turbine was probably beyond airworthyness certification and thus scrap anyway), but I find his "friendly trolling" charming in a surprisingly deep way.
For a stunt car like this there's not a huge need or desire to have it powering the wheels at all.
The direct air thrust will push the car just fine, doesn't need a transmission, has zero issues with wheel spin or traction, and so then doesn't require re-engineering the wheels/tires and then the suspension and/or chassis to handle 1350hp.
Careful wording to give the impression that the drive shaft of the helicopter turbine would be connected to the rear wheels, without actually claiming that it is. So it's a car with a large flame thrower in the back, minor The Boring Company vibes.
Well possible that the author might have had more fun writing than building/driving. (I do love the incredulous tone of "#1 Does this mean I’m the right hands?")