The 2J had two snowmobile engines turning props that sucked the car to the ground. The boxy back end with enclosed wheel wells kept the air in and created the suction footprint.
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I have a cool Tyco HO racer from childhood like the one in this pic..
Jim Hall created some of the most innovative Can-Am race cars of all time. To read more about the man and the cars there's this cool book (click on picture to buy from Amazon):
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If you'd rather race than read there's this cool Scalextric slot car:
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