Adding more fuel to the growing feud between Ford and Tesla, a Ford executive had a snappy rejoinder ready for Elon Musk when the Tesla CEO tweeted on Sunday that the company hit its production goals.

In response to Musk’s announcement, Steve Armstrong, Ford’s president of the Europe, Middle East and Africa region, tweeted how long it takes Ford to make the same number of cars. The tweet invites comparison of the two companies’ production times: seven days for Tesla versus four hours for the more established auto manufacturer.

armstrong tweet

This is not the first time — or even the first time in a week — that the two auto manufacturers have traded barbs.

Last Thursday, Mark Truby, Ford’s vice president of communications, hit back at Musk after the Tesla CEO told The Wall Street Journal that Ford resembles a morgue.

In a since-deleted tweet, Truby called Tesla’s manufacturing facilities a “makeshift tent” and casually mentioned that the Ford Rouge Factory has an F-150 roll off its production lines every 53 seconds.

Although Tesla has yet to record a profitable year, its market value of $56.8 billion tops that of traditional automakers General Motors and Ford. General Motors has a market cap of $55.3 billion, while Ford’s value sits at $43.0 billion. Both companies produce many more vehicles than Tesla.

For months, Tesla has been trying to reach a production rate of 5,000 Model 3 electric cars per week. The car, a sedan priced lower than Tesla’s other models, is the company’s attempt to reach a larger, mass market. But it has been plagued by production snafus and previously missed this milestone.

Even now, that production is running at a faster pace, Tesla is still not making the lower-priced $35,000 version of the Model 3, but a higher-priced version instead.