Poly Engine what was good/bad about it and why is the LA better?

Touche, although arguably the star of Bullitt was the Mustang, not the Charger. Great, realistic appearing chase scene, except it's convinced a lot of people that a 390 Mustang was faster than a Charger R/T, when in reality even though the Bullitt Mustang's 390 was modified, it still couldn't hang with the Charger's stock 440.
But it could be argued that the Charger stole the show! :)