You will find out that soldering is not all that easy. Orienting the wire while holding the terminal end in some clamp or other. You need two hands to solder. Then you will melt the insulation. The heating of the insulation and the solder on the joint, will cause the termination to be overly stiff and not flexible. Then getting solder on a place that won't allow terminal to be installed in a connector shell. Screwing up the connector shell trying to get it in there. You may have "cold" solder joints you won't see. Not to mention it will take you forever to finish.

A good crimp contact using a good crimp tool is plenty good for automotive. Solder is not necessary. The crimps will not come loose.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn