In the first half of 2008, Toyota Financial Services replaced longtime leader GMAC Financial Services as the biggest U.S. auto lender, a new study suggests. The shifts in the captives’ rankings reflect changes in the relative financial health of their parent companies. Automakers use their captives to provide consumer incentives that greatly affect their dealers’ ability to sell new and used vehicles. AutoCount, a research unit of the Experian Automotive marketing information company, estimates Toyota Financial had a 6.35 percent share of the U.S. market for vehicle finance and lease contracts from January through June, compared with 6.20 percent for GMAC. The study does not provide figures on contract volume. Because GMAC has made major cutbacks in U.S. auto leasing this summer, Toyota’s captive finance company could remain ahead of its General Motors competitor for all of 2008, the AutoCount study suggests.