There is no special bankruptcy provision for your business vehicle in Chapter 7. You are entitled to allocate your exemptions so as to protect as much property as you can. And, although you can combine your available exemptions on a single asset, depending upon the choices made when you filed the petition, you may have only exempted a portion of your business vehicle. To the extent that the vehicle is nonexempt, the trustee can have it sold to pay your creditors.
You could conceivably ask the court to permit you to amend your original petition, but the trustee would almost certainly claim that this prejudices your creditors, and your request would be denied, because as you have already had the discharge, your creditors have relied on the petition in the distribution of whatever assets you had at the commencement of the case.
Your attorney may have committed malpractice, if the choices made re your exemptions were unreasonable. But, that doesn't change the trustee's rights. You would have to sue your lawyer.
For a malpractice lawyer referral, see: http://www.abanet.org/legalservices/lris/directory/main.cfm?id=MI and www.martindale.com.
Hope this helps.
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