British automakers who may be eyeing lucrative U.S. markets as an alternative to sales that could be lost if the U.K. quits the European Union as planned could be disappointed, experts say.

This is despite data released last month by the U.K.’s Society of Motor Manufacturers & Traders indicating exports of U.K.-made cars to the U.S. rose 7% year-on-year in 2017 to almost 210,000 units.

Britain’s pending “Brexit” departure from the EU in March 2019 could end the U.K.’s tariff-free trade with the bloc’s remaining 27 member states, defaulting to World Trade Organization 10% tariffs on automobiles if the U.K. fails to negotiate a replacement or interim deal in the next 12 months.

This may push U.K. automakers to try to expand sales in other markets, including the U.S., which sets tariffs of just 2.5% on automotive imports.

According to the SMMT’s analysis, the U.S. is the British automotive sector’s second-largest trading partner after the EU, accounting for 15.7% of its car exports. The industry association says the figures are evidence of the increasing popularity of the U.K.’s “ever-growing range of premium, luxury and sports cars” in America.

“It is vital that we maintain open trade links with the U.S., as well as our EU partners, for the benefit of consumers and our respective industries and economies,” SMMT CEO Mike Hawes says.

However, the SMMT declined to respond directly to WardsAuto requests for comments about whether it believes U.K. exports to the U.S. can replace a meaningful proportion of sales to the EU that might be lost in the event of a WTO-default Brexit deal.

The U.S.’s National Automobile Dealers Assn. is doubtful, saying “most (U.S.) dealers do not have U.K.-built vehicles on their radar.” A NADA spokesperson adds the association is not aware of any data that would support an assertion that British cars are poised to command a substantially bigger share of the U.S. market.

The Michigan-based Center for Automotive Research (CAR) also is dubious about the prospect of a near-term hike in British car imports.

“U.K. imports’ share of total U.S. imports has not yet come back to the pre-recession levels reached between calendar 2003-2005,” a CAR spokesperson says. “The U.S. could be an attractive option for U.K. exports should the Brexit deal end badly for automotive trade with the EU, but the U.S. can only absorb so many U.K. exports.”