Year-to-date, the ETFS Physical Platinum Shares (NYSEArca: PPLT), the lone U.S.-listed ETF backed solely by physical holdings of the white metal, is down 7.3%. That sounds bad, but when measured against the largest gold ETF (down almost 21%) and the largest silver ETF (down nearly 26%), PPLT looks pretty good.

Things could get even better for PPLT and the ETFS Physical Palladium Shares (NYSEArca: PALL). PALL is the best-performing physically backed precious metals ETF with a year-to-date gain of 5.1%. Predictably, the catalyst forcing both platinum and palladium, the less expensive of the two metals, into extended supply shortages is robust global oil demand. [Global Auto Demand to Lift Palladium ETFs]

Both metals will be in a shortage for the longest stretch since 2005 for platinum and 2000 for palladium, Bloomberg reported, citing data from Barclays and Johnson Matthey.

Palladium demand will exceed output by 1.33 million ounces in 2013. Adding to the bullish outlook for palladium futures and PALL is speculation that sales from Russia, the world’s largest producer of the metal, are expected to fall. Russia does not reveal exactly how large its palladium reserves are, but some market observers have theorized the country’s output has been declining for several years. [Palladium ETF Soars]

South Africa is the world’s largest platinum producer and the second-largest palladium producer. Bolstering the case for both white metals is this: Growth in car sales is projected to accelerate to 4.8 percent in 2014 from 2.7 percent this year, Bloomberg reported. The metals are essential in the production of catalytic converters.