With the bag of holding you can carry an infinite amount of stuff in one car. That makes it the single most useful car in the world and the 4k tier is mid in comparison.
Edit: never mind, only 500 lbs. But bag itself is 15 lbs so you stuff things in and their weight no longer matters. No need to upgrade springs and engine to carry a bunch of loot
I like openkuse more. In Estonian, kuse is either imperative form of the verb to pee, or the possessive case of the noun.
Though admittedly I used OpenKuse and it was super reliable for me.