Advance Auto Parts (NYSE: AAP) had a sluggish finish to its 2019 fiscal year. The leading auto parts retailer on Tuesday announces surprisingly weak fourth-quarter sales results while issuing a mixed outlook for 2020. Image source: Getty Images. What happened? Sales gains at existing stores, or comps, slowed to a flat result in the quarter, compared to 1.2% in the prior quarter. The sluggish result surprised management, who cited a "challenging demand environment" in a press release to investors. Comps landed at 1.1% for the full year compared to over 2% in 2018. On the other hand, Advance Auto Parts noted increase profit margins despite heavy spending in areas like the e-commerce business. Adjusted operating profit rose 6% for the full year, up to $677 million. What's next? CEO Tom Greco and his team issued a mixed outlook for 2020. Comps are predicted to range from flat to a 2% increase, which leaves open the possibility of a second straight year of decelerating sales growth. The consumer retailer's expense discipline and pricing power, meanwhile, should contribute to solid earnings gains as operating profit margin rises to between 8.4% and 8.7% compared to 8.2% in fiscal 2019. 10 stocks we like better than Advance Auto PartsWhen investing geniuses David and Tom Gardner have a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* David and Tom just revealed what they believe are the ten best stocks for investors to buy right now... and Advance Auto Parts wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of December 1, 2019 Demitrios Kalogeropoulos has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source