<Where>
    <Or>
        <Or>
            <Eq>
                <FieldRef Name='VehicleLine' />
                <Value Type='Text'>Test1</Value>
            </Eq>
        </Or>
    <Or>
            <Eq>
                <FieldRef Name='VehicleLine' />
                <Value Type='Text'>Test2</Value>
            </Eq>
        </Or>
    <Or>
            <Eq>
                <FieldRef Name='VehicleLine' />
                <Value Type='Text'>Test3</Value>
            </Eq>
        </Or>
    </Or>
</Where>

DECLARE @VehicleLines VARCHAR(50)='Test1','Test2','Test3'; --it can anything (based on user selection)

SELECT * FROM Master WHERE VehicleLine IN (@VehicleLines)