10. Buick Lucerne
> Decrease in units sold: 62,266
> Pct drop: 71.5%
> Base car price: $29,730
> Fuel efficiency: 17 city, 27 hwy

> JD Powers quality score: 4/5
> JD Powers reliability score: 4.5/5

The Lucerne was introduced in 2005. Sales have dropped so much that the car was discontinued this year and production stopped in the early summer. Buick may have positioned the car badly. It has been marketed as a full-sized sedan to compete with mid-priced luxury vehicles made by Lexus, Acura, Lincoln and Mercedes. The Lucerne may be less expensive than those models, but buyers do not consider it in the luxury vehicle class.

9. Chevy Colorado
> Decrease in units sold: 62,977
> Pct drop: 67.2%
> Base car price: $17,395
> Fuel efficiency: 18 city, 25 hwy (for 4-cylinder)
> JD Powers quality score: 3.5/5
> JD Powers reliability score: 3/5

The Colorado is Chevy’s mid-sized pickup, and within the GM family, it competes directly with the GMC Canyon. Both were introduced in 2004. The truck may have too much competition to lift current sales by any significant level. It sits in a segment of the SUV market that includes the Ford (NYSE: F) Ranger, the Toyota Tacoma, and the Nissan Frontier.

8. Toyota Avalon
> Decrease in units sold: 64,325
> Pct drop: 69.6%
> Base car price: $33,195
> Fuel efficiency: 20 city, 29 hwy
> JD Powers quality score: 3/5
> JD Powers reliability score: 4/5

The Avalon is Toyota’s mid-priced, large-sized sedan. Overall, Toyota sales suffered this year after much of the company’s Japan production was shuttered because of the March earthquake. It is only now resuming in full. The Avalon is in a highly competitive portion of the market. Every major car company has a vehicle with similar characteristics and comparable price levels. Hyundai’s success in this part of the market has been remarkable over the past three years. The Avalon was first introduced in 1994 and is on its third generation.

7. Dodge Dakota
> Decrease in units sold: 70,039
> Pct drop: 83.8%
> Base car price: $23,210
> Fuel efficiency: 15 city, 20 hwy
> JD Powers quality score: 3.5/5
> JD Powers reliability score: n/a

The Dakota, marketed under the Ram brand, is a mid-sized pickup. It was introduced in 1986. The current, third generation of the truck was launched in 2005. The version was offered with only a club cab with two rows of seats. The Dakota was discontinued this year, with the last one being produced in August.

6. Chevy Tahoe
> Decrease in units sold: 75,814
> Pct drop: 50.9%
> Base car price: $37,980
> Fuel efficiency: 15 city, 21 hwy
> JD Powers quality score: 4/5
> JD Powers reliability score: 3.5/5

The Tahoe is Chevy’s full-sized SUV. Fully loaded with factory-installed features, the Tahoe can retail for as much as $55,000. The Tahoe also has direct competition within the GM family — the GMC Yukon. In addition, virtually every other U.S. and foreign car company has a vehicle in the same market segment. The truck was first sold in 1995. The current generation of the Tahoe, and the Yukon, were both introduced in 2007.