The European Union Commission is preparing to introduce tariffs on $US20 billion of US goods if Washington imposes trade levies on imported cars, EU trade commissioner Cecilia Malmstrom says.
"We hope that it doesn't come to that and that we can a solution. If not, the EU Commission is preparing a rather long list of many American goods. It would be around $US20 billion ($A27 billion) ," she told the Swedish newspaper Dagens Nyheter on Wednesday.
Any new European tariffs would not be directed at specific American states, she said.
"No, now it's more general goods such as agricultural products, machinery, high-tech products and other things," she said.
She said she did not think US Treasury Secretary Steven Mnuchin's proposal to drop tariffs, non-tariff trade barriers and subsidies was serious, pointing out the US had laws and subsidies protecting American industries.
"We tried earlier in TTIP negotiations to make the United States loosen those laws. It was completely impossible. They did not move a millimetre," Malmstrom told Dagens Nyheter.
Malmstrom, accompanied by European Commission President Jean-Claude Juncker, is in Washington for talks on Wednesday on a long-term trade deal.
It comes a day after the US president called the European Union a "big abuser" of trade relations.
Trump last month slapped tariffs on steel and aluminium from the EU, which replied with hiked import taxes on $US3 billion worth of US goods, politically targeted products ranging from peanut butter to whiskey and motorcycles.
EU automotive exports to the US are worth more than 50 billion euros ($A78.8 billion) annually.
"Steel and aluminium measures turned rhetoric into reality, but doing the same on cars would create a grim new reality indeed," Malmstrom said last week.
In a speech to a meeting of military veterans in Kansas City, Missouri, Trump blasted the EU, complained about China's car tariffs and called existing US trade agreements "a disaster".
He also tweeted on Tuesday night that both the US and the EU should drop all tariffs, barriers and subsidies.
"That would finally be called Free Market and Fair Trade!" Trump said. "Hope they do it, we are ready - but they won't!" he said.
