Are indycars all the same (same frame same engine) or is thre more liberty than say in champ car?

Question

similiar to formula one, but not to that extend.

Answer 1

They both were spec series, but there is more freedom in IndyCar in terms of legal modifications to the cars.

Answer 2

They are all the same. There is no more Champ Car since the two  have reunited. Until a few years ago, there were multiple engine and chassis suppliers that were used but in order to cut down costs, the IRL went to a single engine and chassis.

Champ car had gone to a single chassis supplier last year with the Panoz.

The latest news is that Honda would like to see another engine supplier because they want more competition.

Answer 3

The IndyCars have become what Champ Car used to do, become a spec series. One chassis, one engine manufacture to keep cost down, and it has worked, but didn't create a parity like NASCAR has.

As always, money will determine the success of a team.