There's been a lot of hype around this summer’s "Cash for Clunkers" campaign, which offers a financial incentive for replacing gas guzzlers with more efficient vehicles.

Why stop at cars?

Have you seen your portfolio lately? Despite the rallying equity prices in recent months, not every stock is providing the same kind of mileage given the same tank of gas. If you look hard enough, I'm sure you'll find a clunker or two in every portfolio.

And the beauty of playing "Cash for Clunkers" with your own portfolio is that Uncle Sam isn't on the hook for your trade-in rebate. Your financial incentive rests in the greater capital appreciation that you will potentially earn from owning superior stocks.

Everybody wins, so let's go over three clunkers and three promising replacements.

Clunker: Garmin (NASDAQ:GRMN)
There was a time when owning a Garmin GPS was the ultimate in road-warrior showboating. The turn-by-turn navigation meant never having to pull into a gas station for directions in the wee hours. The "give-a, give-a, give-a, give-a Garmin" holiday commercials were only mildly annoying.

It's a whole new world these days. Year over year, sales fell 27% in Garmin's latest quarter. Earnings fell even harder. The stock still rallied on the news, cheered by sequential improvement from the first quarter of 2009. This may be an encouraging sight, but there is little reason to believe that Garmin will ever be anything close to the company it used to be. The convergence of gadgets and perpetual connectivity has delivered new ways to make sure that we're never lost again.

Replacement: Apple (NASDAQ:AAPL)
I stored away my Garmin nuvi the moment I activated my iPhone. In a pinch, I can fire up Google Maps or any other online mapping site and route my way for free. It's at this point where Garmin fans point out that Google won't offer me turn-by-turn voice prompts or corrective rerouting on the fly. Well, several apps do, including the new TomTom program, which runs $99 -- steep by App Store standards, but still way cheaper than any clunky Garmin contraption.

And, yes, Garmin has smartphone apps, too. But that doesn't change my bearish thesis. The price of navigational assistance is falling sharply, and with it goes Garmin's near-term prospects. 

Clunker: H.J. Heinz (NYSE:HNZ)
There was a time when investors flocked to food companies under times of financial uncertainty. Good times or bad, folks always have to eat. The problem, unfortunately, is that consumers are turning away from many of the leading supermarket brands. When times are tight, saving a couple of quarters on ketchup by buying the store brand over a Heinz bottle is reasonable.

The brands are then forced to either slash prices, ramp up the couponing, or relinquish market share. The bottom line gets hurt regardless of the chosen path. Analysts see Heinz earning $2.69 a share this fiscal year, less than the $2.90 a share it earned a year ago. Even next year's profit target of $2.89 a share doesn't quite catch up to last year's earnings.

Replacement: Green Mountain Coffee Roasters (NASDAQ:GMCR)
The logical plays for slammed brands rest in the companies that make the cheaper store brands, but let's go with some real morning fuel here.

Green Mountain is the company behind the Keurig single-cup brewers that are popping up in home kitchens and office break rooms all over the country. Instead of wasted coffee-pot servings or costly trips to the neighborhood barista, Keurig's K-Cup refills will set java junkies back mere pocket change for a cup of premium coffee. Revenue soared by 61% in the company's latest quarter, with profits skyrocketing 123% higher.

No more slow-rolling ketchup as Carly Simon belts out "Anticipation" for you.

Clunker: Yahoo! (NASDAQ:YHOO)
It's easy to hate on Yahoo! these days. When it handed over its paid-search management and its search technology to Microsoft (NASDAQ:MSFT) last month, it dug its own grave. Yahoo! became Nolan Ryan without his fastball.

However, the dot-com pioneer was already paddling down the stream of obsolescence. A week before its Bing-administered lobotomy, Yahoo!'s second quarter was dreadful. Revenue and operating profits were off by 16% and 25%, respectively. The deal with Microsoft may help the bottom line in the near term, but the top line will be running on fumes for awhile.

Replacement: Baidu (NASDAQ:BIDU)
There's nothing wrong with Big G, but why go with the global leader when China's top dog is moving even faster? Baidu is a speedster, even when the rest of the world is slowing down in a recessionary-cautious zone. During the same three months that found Yahoo! going in reverse, Baidu put the pedal to the metal.

As the world licked its wounds, Baidu delivered revenue growth of 37%, with earnings rising 45%.

Are Baidu shares richly priced? Sure. Investors should have hopped on back in December, when nervous investors bid the stock down to less than a third of today's price. However, as anyone shocked by the Chevy Volt's suggested sticker price of $40,000 will tell you, sometimes you have to pay up for superior mileage.

Do you have any other "clunker vs. replacement" suggestions? Share your picks and pans in the comment box below.

Baidu, Google, and Green Mountain Coffee Roasters are Motley Fool Rule Breakers selections. Apple is a Motley Fool Stock Advisor recommendation. Microsoft is a Motley Fool Inside Value recommendation. H.J. Heinz is a Motley Fool Income Investor selection. Garmin is a Motley Fool Global Gains recommendation. Kick the tires of any of our Foolish newsletter services, free for 30 days.

Longtime Fool contributor Rick Munarriz is not afraid of trade-in values. The road ahead is too promising to warrant living in the past. He owns no shares in any of the stocks in this column and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.