Steve the Sumar Streamliner dates from '55 - that year the Belond Miracle Power Special streamliner made the cut - but sans the cockpit bubble.

As for mid engines - George Bailey made history in '39 when he qualified a Miller mid-engine - and what a simple piece of kit: supercharged and four wheel drive. It qualified 6th but was out after 47 laps.

George Barringer's Tucker Torpedo ran in '46, as did Paul Russo's Fageol Twin Coach Special - it had twin supercharged Offys - the front engine drove the rear wheeels and the rear engine drove the front. It qual'd second but was the first retirement.

Al Miller drove the Preston Tucker thing in '47 and after that, another rear/mid-engined car (because most front engined cars are also 'mid-engined'...I guess) didn't qualify until 1961 when Jack Brabham and the Cooper team arrived.