Add custom fields to checkout

-- url of the page with the problem -- : www.digitalguarddawg.com
-- HikaShop version -- : 2.6.1
-- Joomla version -- : 3.4.8

My client wants to add 3 custom fields to checkout that are mandatory - Year, Make and Model (for cars and bikes).

Is this possible with the out-of-the-box HS Business? Or will it require custom coding? If the latter, can you quote it? Thanks.