Ford's F-Series has been the country's best-selling vehicle for 31 straight years. Photo credit: Ford.

In the land of the free and the home of the brave, it's all about full-size pickup truck sales for Detroit automakers Ford (NYSE:F) and General Motors (NYSE:GM). It's no secret that Ford's and General Motors' full-size pickups bring in the majority of company profits and keep the lights on, thereby making one of the greatest rivalries in the automotive industry sales. Recently, in terms of full-size pickups, Ford has topped General Motors in sales, and that trend looks to continue.

Setting the stage
Already this year Ford's F-Series has surpassed its total number of trucks sold in 2012, more than 645,316 units. If you want to do some math, that means roughly every 42 seconds Ford sells one of its most profitable vehicles to some hungry consumer. That puts Ford easily on pace to win the best-selling vehicle sales title in the United States for the 32 consecutive year – and the best-selling truck for 37 straight years.

"Through October, our leadership margin is nearly 220,000 units over Chevrolet Silverado and 67,000 over Silverado and GMC Sierra combined," said Doug Scott, Ford truck group marketing manager, in a press release. "F-Series has outsold Ram by more than 330,000 units in the first 10 months of 2013, almost 50,000 more trucks than the gap a year ago."

Those results haven't always been the case, and it's only been since the recession that Ford has secured an edge over the Silverado's and Sierra's combined sales.

Graph by author. Information from Automotive News DataCenter. 2013 Projected from sales through October. 

Next year will shape up to be a tighter race as long awaited redesigns of the Silverado and Sierra will have a full year of sales to try to surpass the F-Series, as its next-generation model won't hit the showrooms until spring. However, I'm not so sure General Motors' having a full year of sales with its new model will be enough to turn the tide.

Brand loyalty
Topping the industry in sales for more than three decades means Ford has designed a valuable product that can perform in any rigorous condition, but sustaining success for that long means you're doing other things right.

In the automotive industry, brand loyalty means more than with most retail products. There's a line drawn in the sand between Ford and General Motors -- you're on one side or the other -- and that doesn't change often. You're a Ford guy born and raised, or you're a Chevy guy, period. Looking at information from R.L. Polk Automotive in the first quarter, you can see Ford dominates in brand loyalty, bringing more consumers back to its F-Series, and other models, time and time again.

Graph by author. Information from R.L. Polk & Co. 

It goes deeper than just one survey earlier this year, and according to Ford, it has won the R.L. Polk Automotive Loyalty survey award in the full-size pickup category 15 times in the past 17 years – an absolutely huge advantage when it comes to the two most profitable vehicles in the U.S. market, and the world.

In addition to a solid product, and industry leading brand loyalty, Ford is succeeding because it positions its lineup better than competitors. According to Ford, the F-Series is driving sales in key markets that are leading our country's economic rebound, the Northwest, West, and Southeast, where sales of the F-Series is outpacing the nearest competitor by 50%. Ford also has a new F-150 STX value model that is aimed to customers hit harder by the economic downturn but still have work to do in the housing and energy markets. STX sales surged to 10% of all F-150 sales this year – up from 3% a year ago.

Bottom line
Ford's doing everything needed to continue winning the full-size pickup sales war with cross-town rival General Motors. It has a solid product, a well-positioned vehicle lineup and brand loyalty second to none. General Motors' Chevrolet Silverado has a year before Ford's next-generation F-150 hits the markets, but I believe Ford's trend of out-selling the Silverado and Sierra are here to stay -- and that's great news for Ford fans and investors alike.

Fool contributor Daniel Miller owns shares of Ford and General Motors. The Motley Fool recommends Ford and General Motors and owns shares of Ford. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.