TWR, you are being obtuse.
I will try to state it very clearly.
The OP wants to sell a car on eBay and needs information. You gave bad information because you were referring to professional motor traders and not private sellers.
A private seller can list a car as 'X reg Ford KA' and say nothing more about it. It is 'caveat emptor' - buyer beware.
A private seller can list a car as 'X reg Ford KA, sold as seen'.
If the seller chooses to describe the colour or the mileage, it must be truthful, as far as the seller knows.
A private seller can even say the car is 'a good runner' if that is what they believe it to be. If it has near bald tyres and knackered suspension the seller need say nothing about it. If asked the seller can legitimately say 'it passed the MOT 11 months ago, other than that I haven't looked, checked or noticed anything (if that is the truth).
The only recourse for a private buyer is the small claims' court. Then the buyer would have to prove that he was told, or had in writing, that the seller stated the tyres were new and the suspension recently replaced (or whatever the problem is). Trading Standards do not deal with private sellers, only traders.
You are muddying the waters. The OP merely wants to know if selling a car on eBay is easy and how much it costs.