Are you saying your wife sold a car that was registered to you without your consent? Or are you saying that your wife purported to sell the car or did so and whichever she did she produced a fake invoice for the purposes of the divorce.
From a criminal law point of view this is theft and can be reported as such. I surmise that the police will want to be lazy as always and treat this as a civil matter. However, your were the registered keeper and the owner of the vehicle so this is technically theft. The Scots law definition of theft is the intention to permanently deprive an owner of his property. From a civil law/ matrimonial point of view your solicitor should be raising this as an issue and ensuring that you are fully credited for the true value of the vehicle and not the purported sale price. If the purported invoice is fraudulent then again this raises both civil and criminal connotations. Your solicitor should be taking this on board as should the police. I hope that helps. Please leave a positive rating so that I am credited for my time.