Apologies for posting a non 500, but saw this on a popular auction site and just too nice not to look at on a cold Friday afternoon. Enjoy!

https://bringatrailer.com/listing/1963-fiat-600d-multipla-2/

Wow that’s beautiful. Nuts I thought the $20,000 was the sale price but it’s the current auction bid

The seller mentioned that he had a picture with the engine cover open,to assist cooling. Cobblers----the engine cover on the racing Abarths is NOT primarily for cooling. It was found during testing that the more the engine cover was propped open, the faster the car went, until with the engine cover in the iconic 'open' position, a 1000tc was found to be 6mph faster! Purely by chance (and it was not planned as part of the test session), the tester had created a rear spoiler which gave a much better air flow over the rear of the car---80% aerodynamics and only 20% cooling. However, Mr Abarth decided to kid every body that it WAS for cooling, and until aerodynamics were better understood, he got away with it!

the hobbler said:

The seller mentioned that he had a picture with the engine cover open,to assist cooling. Cobblers----the engine cover on the racing Abarths is NOT primarily for cooling. It was found during testing that the more the engine cover was propped open, the faster the car went, until with the engine cover in the iconic 'open' position, a 1000tc was found to be 6mph faster! Purely by chance (and it was not planned as part of the test session), the tester had created a rear spoiler which gave a much better air flow over the rear of the car---80% aerodynamics and only 20% cooling. However, Mr Abarth decided to kid every body that it WAS for cooling, and until aerodynamics were better understood, he got away with it!

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Slightly off topic -

Walter Kaaden the MZ motorbikes race designer (who worked at what had been the DKW factory before the Iron Curtain came down) discovered the expansion chamber exhaust in a similar way.

Around 1955, he was riding a race 125 that had a simple open megaphone exhaust - just an expanding cone no baffles no nothing else! He fell off and bent the back end of the cone inwards. Riding back to the pits he found the bike had more power with a noticeable step change in delivery.

During WW2 he had worked on pulse jets so understood a bit about speed of sound shockwaves in pipes. Anyways, he invented the exhaust expansion chamber with diverging and converging cones and how the exhaust pipe pressure affected top end power. He tuned that exhaust pumping effect and was the first to get 200bhp per litre from a piston engine and soon enough his 125s were making more than 30bhp.

Just like Abarth with his open engine cover, it was some years before the competition caught up.