What: Shares of TrueCar (TRUE 2.83%) crashed and burned after hours on Thursday when the automotive website announced weak fourth-quarter results, which put the finishing touches on a sobering year.

So what: While the fourth quarter is typically a slow season for the company, it's clear growth has stalled even further than anticipated. TrueCar's average monthly unique users moved 33% higher compared to the prior year's fourth quarter, to 5.9 million, but that growth was much slower than the previous three quarter's of year-over-year gains of 43%, 42%, and 40%. 

The weak user growth was reflected in its units sold, which grew 12% year over year, which was much weaker than the three previous year-over-year gains of 21%, 27%, and 34%. Total revenue during the fourth quarter checked in at $63.6 million, which was below analyst estimates of $65 million, and its year-over-year growth was only 15% -- that growth slowed considerably from the three previous year-over-year gains of 28%, 29%, and 33%.

The worst result, hands down, was found in TrueCar's adjusted EBITDA.

Data source: TrueCar's fourth-quarter presentation.

Now what: With today's sell-off, it appears many investors aren't willing to give newly appointed CEO Chip Perry time to turn the company around. Sadly, with TrueCar projecting 2016 full-year revenue between $270 million to $275 million and $0 million adjusted EBITDA, it's understandable that investors are losing faith. For the record, Wall Street was projecting full-year 2016 revenue between $309 million and adjusted EBITDA of $19.5 million. 

TrueCar, at least to me, was a more than 10-year investment, but the slowing growth, plummeting adjusted EBITDA, and weak guidance this early into the game is concerning. The problem could be that TrueCar is having difficulty getting paid for the sales leads it provides. Investors should look for more color from TrueCar going forward about how the company is improving its website to better lock the consumer into the purchase and how it connects the dots with dealerships to get paid properly. There might be a disconnect in TrueCar's sales funnel, which is then causing the drop in adjusted EBITDA.