10 New-car Clunkers to Avoid

Optimism is a virtue, but there's no place for it in new-car shopping. When out on your test drives, steer clear of these 10 lemons.

With so many worthy new cars and trucks on the market, we had to look long and hard to quantify which just don't make the grade.

So what then separates the true clunkers from the merely mediocre models in dealers' showrooms? We started by finding common threads among quality and reliability ratings from Consumer Reports and J.D. Power and Associates, balanced with the results of our own ongoing new-car test-drives. (Full disclosure: we put at least 75 vehicles through their paces under real-world and higher-performance conditions each year; cars are supplied by automakers for week-long periods, but we do not participate in manufacturer-subsidized preview junkets.)

[More from Yahoo Autos: 5 Used Cars to Avoid]

Of course we're certain that for each of the models cited on our list of new-car clunkers there are myriad satisfied customers who'll swear they've never had a problem with their trusted vehicular companions. That's fine by us. Some of the cars on our list can indeed be enticing if sold at deep discounts and with hefty cash rebates. Still, bargain hunters beware. There are far more worthy models out there from which to choose that perform better and will wind up being superior long-term values.

1. Jeep Liberty/Dodge Nitro

These mechanically equivalent midsize traditional truck-based SUVs deliver stalwart off-road performance when properly equipped, but just feel rough and awkward in normal driving situations. They're underpowered and come only with an antiquated four-speed automatic transmission. Their passenger cabins can be difficult to climb in and out of, with interior comfort lacking. The Liberty offers a unique sliding canvas roof as an option, which disgruntled consumers suggest is problematic. Each gets "below average" ratings from the J.D. Power & Associates Initial Quality and Reliability surveys and from Automotive Lease Guide for residual value.

Consumer Reports lists them among the lowest-scoring new-cars overall, with Intellichoice.com giving them "poor" grades for their relatively high ownership costs. And while these models get "good" ratings for front-impact and roof-crush protection from the Insurance Institute for Highway Safety, they only get an "acceptable" rating for rear-impacts and a "marginal" score for side-impact protection.

2. Chevrolet Colorado/GMC Canyon

Sales of small pickups like this duo from General Motors have fallen through the floor in recent years as buyers discovered they could obtain a full-size hauler with additional capabilities for not much more money. Fitted with either the standard four-cylinder engine or available five-cylinder powerplant, the Colorado and Canyon are best for recreational use only. The trucks' five-speed manual transmission is crude and the optional four-speed automatic is outdated. A V-8 is available, but it's sheer overkill here and specifying it further narrows the price gap between these models and the superior Chevy Silverado and GMC Sierra full-size models.

Both versions received "below average" ratings in the J.D. Power & Associates Initial Quality and Reliability surveys and are projected to retain "below average" resale values according to Automotive Lease Guide. Crew-cab models, which were specifically tested by the Institute for Insurance Highway Safety, earned an "acceptable" rating for occupant protection in frontal collisions, a "marginal" score for roof strength and rear-end impacts and a "poor" ranking for protection in side-impact collisions.

3. Nissan Armada

This behemoth sport-utility vehicle feels every bit as large on the road as it looks and is an unruly handful in urban environments, with parallel parking being particularly challenging. The Armada is, for the most part, an automotive dinosaur, with most SUV buyers having long migrated to more tractable car-based crossover models.

Even among those with purposeful needs, like towing a boat or trailer, it falls short of the competition. The Armada receives "below average" scores in both the J.D. Power & Associates Initial Quality and Reliability surveys and gets a "poor" rating for overall value from Intellichoice.com.

4. GMC Sierra/Chevrolet Silverado 2500

These heavy-duty pickups are built to tackle the toughest jobs, with a maximum towing capacity of 17,500 pounds when properly equipped, but they're hardly amenable as everyday drivers for those merely looking to assume a burly vehicular profile.

The Sierra and Silverado 2500s ranked at number four and five on Consumer Report's least-reliable vehicles list and get "below average" ratings for residual value from Automotive Lease Guide. The standard-duty 1500 models are better choices for truck buyers with more modest needs.

5. Dodge Caliber

This small crossover-like wagon lacks the levels of sophistication and performance found virtually everywhere else in the compact segment. It features dull styling with a cheap-feeling interior, numb handling and lackluster performance from its 2.0-liter four-cylinder engine. Instead of a conventional automatic transmission it offers a gearless continuously variable transmission (CVT) that's whiny and unresponsive.

In addition to being a sub-par overall performer, the Caliber receives a "below average" Initial Quality rating from J.D. Power & Associates, a "below average" residual value projection from Automotive Lease Guide and is ranked as a "poor" value rating by Intellichoice.com. The Insurance Institute for Highway Safety rates it just "acceptable" in rollover roof-crush protection, while its occupant protection in side-impact collisions is ranked as only "marginal."

6. Nissan Titan

Nissan's full-size pickup truck never caught on with U.S. buyers, who tend to be fiercely loyal to their favorite domestic brands. Its model line isn't as diverse as the competition, and it lags behind all of them in terms of performance. On the bright side, it's sold with hefty cash rebates.

The Titan gets "below average" ratings from J.D. Power & Associates for both Initial Quality and Reliability, and gets only a "marginal" rating for side-impact protection with "acceptable" rollover prevention from the Insurance Institute for Highway Safety. It also receives the lowest available ranking for depreciation from Automotive Lease Guide and gets "poor" to ‘below average" value scores (depending on the version) from Intellichoice.com.

7. Smart ForTwo

Sales have dropped off considerably for this oddball tiny two-seat coupe and convertible since its 2008 introduction. It's built in Europe by Mercedes-Benz, but it's hardly a luxury car. Though it feels roomier on the inside than it looks from the outside, it's vastly underpowered, with a fussy automated manual transmission that shifts slowly and sloppily. It boasts good fuel economy at 33/41 mpg, but requires premium-grade gas, which robs an owner of any financial savings at the pump.

The Smart ForTwo posted less than stellar results in government crash tests, receiving only three stars for front-passenger protection and rollover resistance, and this was from the more lenient pre-2011 model-year program. The ForTwo scored among the worst of all vehicles in performance tests conducted by Consumer Reports and garnered the lowest rating for overall value among current small cars. It gets a rock bottom rating for residual value from Automotive Lease Guide.

8. Kia Sedona

The Sedona has been around in its current generation since model-year 2006, which makes it the "oldest" minivan offered in the U.S. While its V-6 engine delivers decent power and it comes with a generous warranty, the Sedona just can't compete with segment stalwarts like the Honda Odyssey and Toyota Sienna in terms of performance and sophistication. What's more it offers only a minimum of family friendly features in a market segment that's defined by its gadgetry.

The Sedona gets "below average" rankings in J.D. Power & Associates surveys for Initial Quality and Reliability. It's rated as being "below average" in projected reliability from Consumer Reports and was cited by the magazine as being the worst value among minivans for 2011. It ranks "poor" in roof-crush protection by the Insurance Institute for Highway Safety and gets a "poor" value rating from Intellichoice.com.

9. Volvo XC90

This seven-passenger luxury crossover offers only a single available engine for 2012, a 3.2-liter inline-six that works hard to get this rather large and heavy vehicle up to speed. It handles rather clumsily, with little in the way of steering feedback. The third-row seat is difficult to access and is suited only for smaller children.

It's also costly and tends to be outclassed by many more-affordable competitors. It gets "below average" reliability marks from Consumer Reports and is rated "below average" in J.D. Power and Associates' Initial Quality and Reliability surveys. It can also be expected to suffer "below average" resale value according to Automotive Lease Guide.

10. Mercedes-Benz R-Class

The midsize R-Class is like a minivan with conventional swing-out doors, and is a costly one at that. One of the brand's lowest-volume models, it tends to get lost in a crowded field of crossover SUVs with its oddly elongated exterior styling, plain-vanilla interior look and sufficient-but-not-exhilarating performance.

Starting at $52,690 it costs almost $11,000 more than a fully loaded Honda Odyssey, which is a far better people mover. It gets a "below average" rating in the J.D. Power & Associates Reliability survey, and Automotive Lease Guide predicts it will deliver below average resale value. It also gets a poor value score from Intellichoice.com for its high ownership costs.