The performance of Australian auto loan asset-backed securities deteriorated in the three months to 31 March 2016, according to Moody's Investors Service. In particular, 30-plus day delinquencies increased to 1.50 per cent at 31 March 2016, up from 1.19 per cent at 31 December 2015, a Moody's media release has disclosed. "The natural amortisation of auto ABS portfolios has also had a large impact on the arrears rates of some older and smaller deals," said Natsumi Matsuda, a Moody's analyst.Despite the increase in delinquencies, default and loss levels remained low. At 31 March 2016, the 2012 vintage - the most seasoned of outstanding pools - had a cumulative default rate of 1.79 per cent and a net loss rate of 0.86 per cent.Performance, however, varied markedly among issuers.The SMART series transactions, backed by loans originated by Macquarie Leasing Pty Limited, demonstrated the lowest weighted-average 30-plus day delinquency rate of 0.72 per cent at 31 March 2016. Even so, this result was up from 0.65 per cent at 31 December 2015 and 0.69 per cent at 31 March 2015.The weighted-average 30-plus day delinquency rate of St George Bank's Crusade transactions increased to 3.23 per cent at 31 March 2016, up from 2.45 per cent at 31 December 2015 and 2.22 per cent at 31 March 2015. Moody's explained that "some operational challenges impacted the collection process" and therefore contributed to the increase in collateral car loans backing the Crusade series. "The servicer expects these issues to be addressed during the second half of 2016," Moody's stated.The weighted-average 30-plus day delinquency rate of BOQ Equipment Finance Limited's REDS transactions increased to 1.71 per cent at 31 March 2016, up from 1.22 per cent at 31 December 2015 and 1.30 per cent at 31 March 2015.Moody's expects delinquencies and defaults to continue to rise throughout the remainder of 2016. In particular, ABS portfolios with exposure to commercial loans and leases in Western Australia and Queensland will come under the most pressure.