LONDON – Rhodium’s on the best run in a decade on expectations of more demand for the material that’s used in cleaning toxic car emissions.

One of the rarest precious metals, it climbed the past seven months and is up 19% this year, outperforming most major commodities. Mostly used alongside palladium in gasoline autocatalysts, prices have rebounded from a 12-year low set in July.

The spectacular turnaround comes amid stronger demand from industrial users including automakers, which account for the bulk of rhodium consumption. China, which predominantly favours gasoline vehicles, in December raised a sales tax on small cars less than originally expected. In 2016, Chinese consumers bought vehicles at the fastest pace in three years.

“China is a big part of this story,” said Jonathan Butler, a precious metals strategist at Mitsubishi Corp. in London. “The level of car ownership is still growing, and there are signs that it could get to western levels.”

The metal is trading at $920/oz, according to Johnson Matthey, which makes about a third of all autocatalysts. This year’s advance compares with a 13% gain for palladium and an 8% increase for platinum, which is also used to curb car emissions. All three metals are mined together, mainly in South Africa.

One way to buy rhodium is through an exchange-traded product started by Standard Bank Group in late 2015. Money managers account for most purchases in the fund and private investors make up the rest, according to Johann Erasmus, who oversees the fund.

The product’s assets total about 46 650 oz, he said. That’s about 5% of total annual demand.

Because rhodium is a smaller market than other precious metals, prices are more volatile, said Grant Sporre, an analyst at Deutsche Bank in London. The metal surged almost 23-fold from 2003 to 2008, when it touched a record $10 100.

“There’s “currently no reason to expect falling prices in the short or medium term,” Heraeus Metals Germany said in a report emailed Monday.