There are lot of free plugin available for xF 1.x
xF 2.x is still in beta stage so very less developer had ported or developed addon for it. in coming future near to end of this year or when first supported release of xF2.x is out, you will find tones of add on for it too.
What you expect at $140 a fully customized Ferrari that to at price with which you cant even buy its engine.
We are getting a same type car at this prize, you should thanks to xF Team for it.
Customization
Test of every one is different, so we should wait at least for some dev to take effort for us to avail flavors at free.
Or take your car to someone's shop and pay for development / mods or get all accessories and do mod on your own.
My Suggestion
You wont need add on unless your website already had it and you are thinking to have it when you shift in other car.
If you are new then, wait for sometime. concentrate on your driving first, get some peoples look at your riding, make them your follower.
After this start thinking to thrill them with new power mods.
Keep in Mind
You get a Ferrari at price of ____________ you might know better than me if you are Fast and Furious.
Yours,
Domnic Torreto
Please don't mind for my words, i like to make example in order to make subject understand better and unforgettable