You can ask, plead, and beg all you want; it will do you no good. Criterion Games is finished making downloadable content for Burnout Paradise, and their mind seems fairly set on that.
A post to their Twitter account earlier today said: “Please stop asking us for Burnout Paradise DLC. There will be no more! Sorry everyone!”
In their defense, however, they did add: “But we did WAY more than everyone else…”
Oh well. At least we got cool versions of some classic, iconic 80’s vehicles like the DeLorean, right?