I was really into SE and i started building my 5X5 mining monster, but got totally disappointed how the wheels and suspension works. Because they dont.
Theres absolutely no grip in those big tires and the suspension modeling is terrible, i just cant live with those..

I have tried changing all stats linked with those but nothing seems to help, the suspension modeling is simply awful and kills my immersion immediately.
Unusual that, as my old build hauler works fine, although this is from a while back. But you do have to take into account the planets gravity, plus all the settings on the build ie; friction, suspension etc.
I have a little 4 wheel fun buggy that is a blast to play around in, although not much good for anything else as it's too small.
I like wheeled vehicles in SE, however, if they're not set up right then you can have problems, but as with many build versions of SE, sometimes you just hit on the wrong build at the time, which may have been what happened to you, not sure.
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Have to put this one in as well.. Not my build, this is much better than I would do, for wheels at least. A nice 'large' rolling fort..
I'm a hover fan myself, rather than wheels..
Edit: SE isn't a pew, pew game really. Where fighting is concerned its better to take the tactical route, ie. fire from a distance. There are plenty of weapons you can build that will do the job, even a simple camera on a drone will do the job for you, flying bomb.
ED has the pew, pew side, for sure. SE is a little more thought out..
Found my hover buggy.. o.k. another video.. I know..
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Flight model wise SE v ED, for me they feel almost the same. This is without inertia dampeners on, fly in a direction and you won't stop until you put some type of force against that direction. It isn't like NMS, arcade style, which I enjoy too.
Ship's in SE however tend to act their size more, large ships, if built nicely, will feel heavy on the whole. Plus vice-versa, my very small bug fighter is very nimble indeed and with a better pilot than me, would do quite well in pew, pew.
Now where planets are concerned these are not realistic in that they will not rotate and there isn't much chance of getting an orbit, although some have got very near using what the game has. They do however have varying gravity pull and atmosphere's (depending on planet). But originally there were not going to be any planets at all. But we as a community kept on asking and finally got them. As they are, are as we take them, and we're thankfull for that too.
There are many things in the game like gyroscopes, artificial mass, gravity gens and so on, that bend all sorts of rules. But the same can be said for most space games, case of give and take plus it is the future...
There are mods that will give you almost anything regards flying you want. But on the whole the game has a good flight model.