I found this skidmark vs. speed calculator.
On zero grade dry asphalt or concrete, the car would of lost about 50mph during a 100 foot skid. But it still smashed over a guard rail and fliped with enough force to disingrate a porsche with a extremely beefy body cage built into the design.
He must of been speeding, at least 80 to 100 mph.
Last news report I saw said his speed was 140 or so. If he left the road doing 90, that’s plenty fast enough...