Potholes. Detours. Slippery spots. Driving is never for the weak of heart, and Ford's(NYSE: F) had a rocky road lately.

The country's second-largest auto maker revealed its projected Q2 production will amount to just 980,000 vehicles. That's a 17% slide from last year's assembly line throughput. And Ford's not the only one hitting the brakes. Earlier this month, General Motors(NYSE: GM) announced it will reduce output, but by only 10%.

You can look at the disparity between Detroit's road warriors in two ways: Either Ford still hasn't shaken the stigma of its Firestone tire fiasco, or the popularity of its beefier trucks and SUVs is waning.

Let's tackle the Firestone flap first. Don't buy it. The federal government concluded its investigation back in 2001. There was more fear and trepidation about the Ford Explorer last year than now. If anything, that should've sandbagged last year's production levels and helped prop up this year's showing.

Are Ford vehicles fading in popularity? Dealers have a glut of inventory. That alone would slam the anti-lock brakes on full-blown production. Making matters worse, car makers have resorted to large cash incentives and cheap financing to move products, and folks are still reluctant to grab the wheel and drive the deal off the lot. Can you get any lower than 0% financing? Buy a car and get a free ham?

Auto makers face the possibility of war and higher prices at the pump, along with the near certainty that the economy isn't going to improve anytime soon. That can't be good for a company with massive debt loads to service.

Don't ignore the warning in Ford's side-view mirror: The problems are closer than they appear.