如何创建正确的Lambda表达式来处理比较两个对象列表？

foreach (DTO.ImportData row in Helper.ImportTracker.ImportsValid)
{
    bool isInsert = false;
    bool isUpdate = false;
    Model.Auto auto = null;

    // Get auto(s) for this SKU + VIN + ClientID...
    var autos = _dbFeed.Autoes.Where(a => a.StockNumber == row.Stock && a.VIN == row.VIN && a.ClientID == _targetClientID && a.SourceClientID == _sourceClientID).ToList();
    if (autos.Count > 1)        // ERROR...
    {
        Helper.ImportTracker.ImportsInvalid.Add(row);
        continue;
    }
    else if (autos.Count == 1)  // UPDATE...
    {
        auto = autos[0];
        if (auto.GuaranteedSalePrice != row.GuaranteedSalePrice ||
            auto.ListPrice != row.ListPrice ||
            auto.Miles != row.Miles ||
            auto.Active != row.Active ||
            auto.MSRP != row.MSRP ||
            auto.InternetPrice != row.Internet_Price ||
            auto.InvoiceCost != row.Invoice ||
            auto.Make != row.Make ||
            auto.Model != row.Model ||
            auto.Year != row.Year 
            )
        {
            Helper.ImportTracker.Updates.Add(row);
            isUpdate = true;
        }
        else
        {
            isUpdate = false;
            auto = null;
        }
    }
    else                        // INSERT...
    {
        isInsert = true;
        auto = new Model.Auto();
        _dbFeed.Autoes.AddObject(auto);
        Helper.ImportTracker.Inserts.Add(row);
    }

    // Fill in the data...
    if (auto != null)
    {
        ...
    }
    // left out for readability - this section just maps the import 
    // data to the table row and saves to the DB...
}

List<import>

List<table>

class TableComparer : IEqualityComparer<table>
{
    public bool Equals(table x, table y)
    {
        if (Object.ReferenceEquals(x, y)) return true;

        if (Object.ReferenceEquals(x, null) ||
            Object.ReferenceEquals(y, null))
                return false;

            return x.SKU == y.SKU && x.VIN == y.VIN && x.ClientID == y.ClientID;
    }

    public int GetHashCode(table table)
    {
        if (Object.ReferenceEquals(table, null)) return 0;

        int hashSKU = SKU == null ? 0 : SKU.GetHashCode();
        int hashVIN = VIN == null ? 0 : VIN.GetHashCode();
        int hashClientID = ClientID.GetHashCode();

        return hashClientID ^ hashSKU ^ hashVIN;
    }
}

var UpdateAutos = autos.Intersect(new TableComparer(imports));
var InsertAutos = imports.Except(new TableComparer(autos));
var DeleteAutos = autos.Except(new TableComparer(imports));

private void HandleAutos()
{
    // convert to List<auto>...
    List<Model.Auto> imports = AutoConvert.Convert(Helper.ImportTracker.ImportsValid, _targetClientID, _sourceClientID, DateTime.UtcNow, _dbFeed);

    // get all DB records in List<auto>...
    List<Model.Auto> current = _dbFeed.Autoes.Where(a => a.ClientID == _targetClientID && a.Active == true).ToList();

    // isolate all Inserts, Updates and Deletes...
    var intersect = imports.Intersect(current, new AutoIsIn());         // should be all autos with matching VIN & SKU  //
    var updates = intersect.Intersect(current, new AutoHasChanged());   // should be a subset of changed resords        //
    var inserts = imports.Except(current, new AutoIsIn());              // should be all the imports not in the DB      //
    var deletes = current.Except(imports, new AutoIsIn());              // should be all the DB records not in imports  //

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace RivWorks.FeedHandler.Library
{
    class AutoIsIn : IEqualityComparer<Model.Auto>
    {
        public bool Equals(Model.Auto x, Model.Auto y)
        {
            if (Object.ReferenceEquals(x, y)) return true;
            if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null)) return false;

            return x.StockNumber == y.StockNumber && x.VIN == y.VIN;
        }

        public int GetHashCode(Model.Auto auto)
        {
            if (Object.ReferenceEquals(auto, null)) return 0;

            int hashSKU = auto.StockNumber == null ? 0 : auto.StockNumber.GetHashCode();
            int hashVIN = auto.VIN == null ? 0 : auto.VIN.GetHashCode();

            return hashSKU ^ hashVIN;
        }
    }

    class AutoHasChanged : IEqualityComparer<Model.Auto>
    {
        public bool Equals(Model.Auto x, Model.Auto y)
        {
            if (Object.ReferenceEquals(x, y)) return true;
            if (Object.ReferenceEquals(x, null) || Object.ReferenceEquals(y, null)) return false;

            return (x.GuaranteedSalePrice != y.GuaranteedSalePrice 
                 || x.ListPrice != y.ListPrice 
                 || x.Miles != y.Miles 
                 || x.MSRP != y.MSRP 
                 || x.InternetPrice != y.InternetPrice 
                 || x.InvoiceCost != y.InvoiceCost 
                 || x.Make != y.Make 
                 || x.Model != y.Model 
                 || x.Year != y.Year
                 );
        }

        public int GetHashCode(Model.Auto auto)
        {
            if (Object.ReferenceEquals(auto, null)) return 0;

            int hashMake = auto.Make == null ? 0 : auto.Make.GetHashCode();
            int hashModel = auto.Model == null ? 0 : auto.Model.GetHashCode();
            int hashYear = auto.Year.GetHashCode();

            int hashGSP = auto.GuaranteedSalePrice.GetHashCode();
            int hashLP = !auto.ListPrice.HasValue ? 0 : auto.ListPrice.GetHashCode();
            int hashMiles = !auto.Miles.HasValue ? 0 : auto.Miles.GetHashCode();
            int hashMSRP = !auto.MSRP.HasValue ? 0 : auto.MSRP.GetHashCode();
            int hashIP = !auto.InternetPrice.HasValue ? 0 : auto.InternetPrice.GetHashCode();
            int hashIC = !auto.InvoiceCost.HasValue ? 0 : auto.InvoiceCost.GetHashCode();

            return hashMake ^ hashModel ^ hashYear ^ hashGSP ^ hashLP ^ hashMiles ^ hashMSRP ^ hashIP ^ hashIC;
        }
    }
}