Can Certificate of Entitlement (COE) prices be benchmarked against household incomes to ensure cars remain affordable for ordinary Singaporeans? MP Yip Hon Weng raised the question in parliament on Tuesday (Nov 3), asking whether an income-linked benchmark could be considered as part of the COE review. In response, Transport Minister Jeffrey Siow explained that COE prices are determined by demand and supply, and that it is difficult to control both the number.