**Exhibit 99.1**     **VolkswagenAuto Loan Enhanced Trust 2005-1** **MONTHLY SERVICER CERTIFICATE**  **Forthe collection period ended 3-31-2006****Data Current as of 4/3/20063:01:09 PM**              ***A.*** ***DATES*** *Begin* *End* *# days* 1 Determination Date   4/18/2006              2 Payment Date   4/20/2006              3 Collection Period 2/26/2006 3/31/2006 34        4 Monthly Interest Period - Actual/360 3/20/2006 4/19/2006 31        5 Monthly Interest - 30/360     30   
***B. SUMMARY***                            ***Initial Balance***  ***Beginning Balance***  ***Principal Payment***  ***Ending Balance***  ***Note Factor*** 6 Class A-1 Notes  285,000,000.00   132,584,728.62   48,030,859.97   84,553,868.65   0.2966802 7 Class A-2 Notes  288,000,000.00   288,000,000.00   —   288,000,000.00   1.0000000 8 Class A-3 Notes  435,000,000.00   435,000,000.00   —   435,000,000.00   1.0000000 9 Class A-4 Notes  226,188,000.00   226,188,000.00   —   226,188,000.00   1.0000000 10 Subordinated Notes  28,408,655.00   28,408,655.00   —   28,408,655.00   1.0000000    11 **Total Securities** **$****1,262,596,655.00**  **$****1,110,181,383.62**  **$****48,030,859.97**  **$****1,062,150,523.65**                                  12 **Net Pool Balance** **$****1,364,964,811.90**  **$****1,196,924,580.26**      **$****1,145,187,523.44**                                           ***Per $1000*** ***Principal & Interest*** ***Per $1000***    ***Coupon Rate*** ***Interest Pmt Due*** ***Face Amount*** ***Payment Due*** ***Face Amount***                  13 Class A-1 Notes  4.3664%  498,512.69   3.7599556   48,529,372.66   366.0253572 14 Class A-2 Notes  4.7300%  1,135,200.00   3.9416667   1,135,200.00   3.9416667 15 Class A-3 Notes  4.8000%  1,740,000.00   4.0000000   1,740,000.00   4.0000000 16 Class A-4 Notes  4.8600%  916,061.40   4.0500000   916,061.40   4.0500000      **Total Securities**      **4,289,774.09**       **52,320,634.06**                                      ***C.*** ***COLLECTIONS AND AVAILABLE FUNDS***     17 Scheduled Principal Payments Received  33,008,018.58 18 Scheduled Interest Payments Received  3,845,355.97 19 Prepayments of Principal Received  279,592.15 20 Liquidation Proceeds  17,750,627.78 21 Recoveries Received  219,600.01 22 Other Payments Received to Reduce Principal  —    23 **Subtotal: Total Collections**  55,103,194.49    24 Repurchased Receivables  — 25 Reserve Account Excess Amount (Item 85)  35,639.68    26 **Total Available Funds, prior to Servicer Advances**  55,138,834.17    27 Servicer Advance (Item 68)  —    28 **Total Available Funds + Servicer Advance**  55,138,834.17    29 Reserve Account Draw Amount (Item 71)  —    30 **Total Available Funds + Servicer Advance and Reserve Account Draw Amount**  55,138,834.17           ***D.*** ***DISTRIBUTIONS***       **Distribution Summary:**    31 Prior Advance Reimbursement (Item 74)  — 32 Servicing Fees (Item 38)  925,151.15 33 Class A Noteholder Interest (Item 47)  4,289,774.09 34 Principal Distribution Amount (Item 72)  48,030,859.97 35 Amount Paid to Reserve Account to Reach Specified Balance  — 36 Other Amounts Paid to Trustees  — 37 Certificateholders PrincipalDistribution Amount  —    38 **Remaining Funds to Certificateholder**  1,893,048.96    

 
     **VolkswagenAuto Loan Enhanced Trust 2005-1** **MONTHLY SERVICER CERTIFICATE**  **Forthe collection period ended 3-31-2006****** **PAGE 2**                  **Distribution Detail:** *Due*  *Shortfall*  *Paid*    39 Servicing Fees  925,151.15   —   925,151.15                     Pro rata:            40 Class A-1 Interest  498,512.69   —   498,512.69 41 Class A-2 Interest  1,135,200.00   —   1,135,200.00 42 Class A-3 Interest  1,740,000.00   —   1,740,000.00 43 Class A-4 Interest  916,061.40   —   916,061.40 44 Class A-1 Interest Carryover Shortfall  —   —   — 45 Class A-2 Interest Carryover Shortfall  —   —   — 46 Class A-3 Interest Carryover Shortfall  —   —   — 47 Class A-4 Interest Carryover Shortfall  —   —   —    48 Class A Noteholder Interest  4,289,774.09   —   4,289,774.09                   ***E.*** ***CALCULATIONS***               **Calculation of Principal Distribution Amount:**            49 Beginning Note Balance - All Classes          1,110,181,383.62 50 Beginning Net Pool Balance      1,196,924,580.26     51 Receipts of Scheduled Principal      (33,008,018.58)    52 Receipts of Prepaid Principal      (279,592.15)    53 Liquidation Proceeds      (17,750,627.78)    54 Other Collections of Principal      —     55 Principal Amount of Repurchases      —     56 Principal Amount of Defaulted Receivables      (698,818.31)                  57 Ending Net Pool Balance      1,145,187,523.44     58 Yield Supplement Overcollateralization Amount      83,036,999.79                   59 Adjusted Pool Balance      1,062,150,523.65     60 Less: Adjusted Pool Balance - End of Collection Period          1,062,150,523.65    61 **Calculated Principal Distribution Amount**          48,030,859.97                     **Calculation of Servicer Advance:**            62 Available Funds, prior to Servicer Advances (Item 26)          55,138,834.17 63 Less: Prior Advance Reimbursement (Item 31)          — 64 Less: Servicing Fees Paid (Item 32)          925,151.15 65 Less: Interest Paid to Noteholders (Item 33)          4,289,774.09 66 Less: Calculated Principal Distribution (Item 60)          48,030,859.97    67 Equals: Remaining Available Funds before Servicer Advance          1,893,048.96 68 Monthly Loan Payments Due on Included Units but not received (N/A if Item 66 > 0)      N/A    69 **Servicer Advance (If Item 66 < 0, lesser of Item 66 and Item 67, else 0)**          —                     **Calculation of Reserve Account Draw Amount:**            70 Remaining Available Funds, before Reserve Account Draw (Item 66 plus Item 68)       1,893,048.96 71 Available Funds Shortfall Amount (If Item 69 < 0, Item 69, else 0)          —    72 **Reserve Account Draw Amount (If Item 70 is > 0, Lesser of Reserve Acct Balance and Item 70)**   **—**                      73 **Principal Distribution Amount (Item 60 - Available Funds Shortfall + Reserve Account Draw Amt)**   48,030,859.97                     **Reconciliation of ServicerAdvance:**            74 Beginning Balance of Servicer Advance          — 75 Less: Prior Advance Reimbursement          — 76 Plus: Additional Payment Advances for Current Period          —    77 Ending Balance of Payment Advance          —    

 
     **VolkswagenAuto Loan Enhanced Trust 2005-1** **MONTHLY SERVICER CERTIFICATE**  **Forthe collection period ended 3-31-2006****** **PAGE 3**            ***F.*** ***RESERVE ACCOUNT***           **Reserve Account Balances:**        78 Specified Reserve Account Balance(Lesser of (a) $9,469,474.91, and (b) the aggregate note balance) 9,469,474.91 79 Initial Reserve Account Balance      6,312,983.28            80 Beginning Reserve Account Balance      9,469,474.91 81 Plus:  Net Investment Income for the Collection Period      35,639.68    82 Subtotal:  Reserve Fund Available for Distribution      9,505,114.59 83 Plus:  Deposit of Excess Available Funds (Item 35)      — 84 Less:  Reserve Account Draw Amount (Item 71)      —    85 Subtotal Reserve Account Balance      9,505,114.59 86 Less: Reserve Account Excess Amount to Available Funds (If Item 84 > Item 77)      35,639.68    87 **Equals: Ending Reserve Account Balance**      9,469,474.91               88 **Change in Reserve Account Balance from Immediately Preceding Payment Date**      —               ***G.*** ***POOL STATISTICS***           **Collateral PoolBalance Data:** ***Initial*** ***Current***          89 Net Pool Balance  1,364,964,812   1,145,187,523 90 Number of Current Contracts  84,775   78,961 91 Weighted Average Loan Rate  3.42%  3.39%92 Average Remaining Term  48.9   44.8 93 Average Original Term  57.9   58.2                               ***Outstanding***  **Net Credit Lossand Repossession Activity:** ***Units***  ***Principal Balance***        94 Aggregate Outstanding Principal Balance of Charged Off Receivables  41   698,818 95 Liquidation Proceeds on Related Vehicles      — 96 Recoveries Received on Receivables Previously Charged Off      219,600    97 Net Principal Losses for Current Collection Period  41   479,218    98 Beginning Net Principal Losses  102   1,629,269 99 Net Principal Losses for Current Collection Period  41   479,218    100 Cumulative Net Principal Losses  143   2,108,488                               ***Outstanding***  **DelinquenciesAging Profile - End of Period:** ***Percentage*** ***Units***  ***Principal Balance***            101 Current  99.45%  78,524   1,138,894,033 102 31 - 60 Days Delinquent  0.51%  413   5,891,968 103 61 - 90 Days Delinquent  0.04%  24   401,523    104 **Total**  100.00%  78,961   1,145,187,523