Car photos taken inside under fluorescent lighting I find notoriously difficult to get a good image. The lights above reflect off the shiny polished curved surfaces and inevitably blow out into hot spots - nothing I can suggest to fix this, even with lots of accessory lighting like high powered flash will make little difference. I tend to look at these as a memory of the day rather than the making of great art. Other guys will always be keen to see what you have and won't care about technicalities.
I do find the 28mm focal length to often be idea both to get the whole car in and good close up detail of larger parts. 28 also is ok for interiors if you can get access inside.
It seems you did have some underexposed for some reason?
I am trying to work out what the car in the first set #113 is??... I've seen it but got me beat?https://www.dropbox.com/sh/y9v3nt7y99sett6/JViaJ5aTsF#f:R0021187.JPG
On the whole an enjoyable bunch of cars!