Consular application and reciprocity fees for each family member, escrow and legal fees on the purchase, a business valuation or due-diligence review, U.S. entity formation, and interest on the home line of credit. None of these count as investment, and consultation fees sit outside them.
Budget the transaction, then budget the visa
The investment figure the officer measures is the capital committed to the enterprise: the cash and home-secured funds paid for the business plus working capital placed in its account. Everything else is expense. On the transaction side there are legal fees for the purchase agreement and escrow, a broker's commission if one is involved, due diligence on the car wash's equipment and environmental compliance, and formation of the U.S.
entity that will own it. On the immigration side there are the Department of State's E-visa application fee and any reciprocity charge for each applicant, and the cost of preparing the application. Interest on the home line of credit is a personal cost and continues whether or not the visa issues.
Renewals of E-2 status carry their own fees over time. Keep these separate from the investment in the couple's own accounting, because describing legal fees as part of the investment weakens the substantiality showing rather than strengthening it.