Bogan would likely have to forfeit the money that he received for the car wash. Whether or not he knew or suspected that Walter White had earned the money Illegally, it was still the proceeds of criminal activity.When Skyler was eventually questioned about how she and Walt were able to buy the car wash, if she was granted immunity for her testimony she would then have to reveal the origin of their funds.
That means the car wash would be seized AND the money used to purchase the car wash would also be liable to civil forfeiture. If Bogan were lucky and hired a good attorney he could perhaps get the car wash back as the use of criminal funds could possible construed as having render the sales contract written for the business fraudulent. However, it's likely that he would lose both the money AND the car wash in the deal.
The fact Bogdan didn't know the source of the funds is irrelevant. If you receive money from an illegal source and the amount is beyond a minor amount (the carwash was purchased for $845,000 USD, not an insignificant sum) to presume as the other answer to this question does, that the US government would not attempt civil forfeiture demonstrates a basic misunderstanding of US federal law and jurisprudence.