You call that the most realistic? If you can't even get the car to be like it's RL weight, there's something wrong with your modding. OT (repost):
Weight doesn't do much for handling if you don't fine tune the JBeam. All you're doing at this point is embarrassing yourself by failing to recognize that your mod needs work and isn't perfect. The JBeam picture you uploaded wasn't very good, and it's clear that you need a lot more practice before that will be close to being ready for a beta or even an alpha release. The K-Series is also an entirely different type of car than a Challenger, so I hope you've made a lot of changes in that JBeam to reflect that.
It says right there what it is: I have all sorts of weird private things That for example does nothing really, it is useful when testing different paints, but by itself it is nothing really. This green thing slides on those rails on base frame, it is useful to me, but there is no any kind of graphics so it is not really anything release worth: So tools that are not much use for anyone else.