Arguably up to 2017, WEC LMP1 was the most cutting edge in regards to Cars.
I guess you could say F1 is cutting edge in regards to budget and perhaps some aspects of design and power plants... but the racing sucks
Indycar today is CART 2.0. The split sucked. My formative years gaining perspective on auto racing came during the worst years of the split. While it was great being able to watch 2 American OW races on Sundays in the spring/summer, the damage to the sport because of ego sucked.
I'm not saying Indycar is the most technologically advanced, popular, or prestigious series in the world- I'd kill to have the declining crowds and TV ratings of NASCAR. But other than Global Rallycross and maybe Formula E it is the only major motor racing series actually growing- TV ratings have modestly risen over the previous few years, the racing is incredible, a spec chassis and 2 unique engine MFGs allow for a level playing field that produces the purest form of High Level Motorsport on the planet- Where else can a guy like Sebastian Bourdais (arguably one of the world's greatest drivers) in an underfunded team dominate a street course like St Petersberg last year?
Case in point, the split happened almost 22 years ago. Indycar is trying to pick up the pieces and while the damage has been done, if you like good racing in its purest sense and appreciate the lore, and tradition of the oldest form of racing in the United States its worth spending an a couple hours watching an Indycar race
Unrelated:
A great throwback to the good ol days
https://www.youtube.com/watch?v=1ikq2G-qakY
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