Federal Reserve Chairman Jerome Powell announced the fourth interest-rate hike of the year while downgrading central bankers' expectations for economic growth in 2018 and 2019.

The federal funds rate, which controls the cost of home and auto loans, among other forms of borrowing, now stands at 2.25% to 2.5%. The move comes as no surprise to market watchers but nonetheless concludes a 12-month period in which interest rates rose faster than in any time since 2006.

Citing emerging "cross-currents" that could slow a still-booming economy, Powell also announced a slight downgrade to its economic growth forecast to 3.0% for 2018 (down from 3.1%) and 2.3% for 2019 (down from 2.5%).

"Despite this robust economic backdrop and our expectation for healthy growth, we have seen developments that may signal some softening," Powell said.

Cox Automotive Chief Economist Jonathan Smoke noted that the latest hike comes at a time when rates for auto loans have reached a seven-year high.

"If we see rates move up by more than a quarter point, they will be in the range we saw back in early 2011 and before that 2004," Smoke said. "The era of low auto loan rates is clearly behind us. That means that the payment becomes even more front and center to the car-buying experience. Negotiating the payment is ironically the part of the buying process that consumers dislike the most and want to change."