As used in this chapter, unless the context requires a different meaning: “Commissioner” means the Commissioner of the Department of Motor Vehicles of the Commonwealth. “Department” means the Department of Motor Vehicles of the Commonwealth, acting through its duly authorized officers and agents. “Mobile office” means an industrialized building unit not subject to the federal regulation, which may be constructed on a chassis for the purpose of towing to the point of use and designed to be used with or without a permanent foundation, for commercial use and not for residential use; or two or more such units separately towable, but designed to be joined together at the point of use to form a single commercial structure, and which may be designed for removal to, and installation or erection on other sites. “Motor vehicle” means every vehicle, except for mobile office as herein defined, that is self-propelled or designed for self-propulsion and every vehicle drawn by or designed to be drawn by a motor vehicle, including all-terrain vehicles, manufactured homes, mopeds, and off-road motorcycles as those terms are defined in § 46.2-100 and every device in, upon and by which any person or property is, or can be, transported or drawn upon a highway, but excepting devices moved by human or animal power, devices used exclusively upon stationary rails or tracks and vehicles, other than manufactured homes, used in the Commonwealth but not required to be licensed by the Commonwealth. “Sale” means any transfer of ownership or possession, by exchange or barter, conditional or otherwise, in any manner or by any means whatsoever, of a motor vehicle. “Sale” also includes a transaction whereby possession is transferred but title is retained by the seller as security. “Sale” does not include a transfer of ownership or possession made to secure payment of an obligation, nor does it include a refund for, or replacement of, a motor vehicle of equivalent or lesser value pursuant to the Virginia Motor Vehicle Warranty Enforcement Act (§ 59.1-207.9 et seq.). Where the replacement motor vehicle is of greater value than the motor vehicle replaced, only the difference in value shall constitute a sale. “Sale price” means the total price paid for a motor vehicle and all attachments thereon and accessories thereto, as determined by the Commissioner, exclusive of any federal manufacturers’ excise tax, without any allowance or deduction for trade-ins or unpaid liens or encumbrances. However, “sale price” does not include (i) any manufacturer rebate or manufacturer incentive payment applied to the transaction by the customer or dealer whether as a reduction in the sales price or as payment for the vehicle and (ii) the cost of controls, lifts, automatic transmission, power steering, power brakes or any other equipment installed in or added to a motor vehicle that is required by law or regulation as a condition for operation of a motor vehicle by an individual with a disability.