The "cash for clunkers" bill working its way through Congress would pay car owners up to $4,500 (via government vouchers) to replace vehicles getting 18 miles per gallon or less with new, more-fuel-efficient models. This list offers snapshots of most popular models that would qualify as clunkers and ordinarily be unlikely to bring in $4,500 in trade-ins.

All mpg figures are combined city and highway mileage according to the Environmental Protection Agency. Estimated values vary based on location (this slide show uses estimates for West New York, N.J.).

1989 Acura Legend sedan, four-door model with automatic transmission

Trading in this car in most circumstances would bring you only about $475. But because the automatic gets 18 miles per gallon, it could net an owner up to $4,500 in the cash-for-clunkers program. Other Acuras, including most models of the NSX, would qualify from a fuel-efficiency standpoint. But they'd be worth more in a sale, unless they were in really terrible condition.

For more about Acura vehicles, go to MSN Autos.

2002 Buick Rendezvous CXL all-wheel-drive SUV

Even in excellent condition, this car still qualifies as a clunker. Its average trade-in value is less than $4,200, and it gets just 18 mpg.

For more about Buick vehicles, go to MSN Autos.

2001 Cadillac DeVille sedan

The DeVille gets about 18 mpg and generally is worth a little less than $2,850 in a trade-in. It wouldn't be the only Cadillac to qualify for a clunker voucher. Most models of the Catera and the Eldorado made before 1999 would qualify and be well worth the vouchers.

For more about Cadillac vehicles, go to MSN Autos.

1999 Chevrolet Astro van

At only 15 mpg, this van is a big gas guzzler. But under the cash-for-clunkers program, that would be a good thing, because the government vouchers would be worth more than the average trade-in value. Some other Chevrolets that would meet the mpg standards: the Blazer, Venture, Tahoe, Trailblazer and Silverado.

For more about Chevrolet vehicles, go to MSN Autos.

2002 Chrysler Town & Country LX minivan

This car gets about 17 mpg and usually nets about $3,675 on a trade-in -- which would make it worth doing through the cash-for-clunkers program if the owner upgraded to a car that got 10 mpg more and thus qualified for the full $4,500 voucher.

For more about Chrysler vehicles, go to MSN Autos.

The Durango gets between 12 and 14 mpg, depending on the model. That would make it easy to find a vehicle that met the necessary mileage improvements to qualify for the full government voucher. The 1999 model generally brings in less than $2,800 in good condition.

For more about Dodge vehicles, go to MSN Autos.

2003 Ford Crown Victoria sedan

Newer versions of the Crown Victoria still get 18 mpg or less but are worth more than $4,500 in a trade. The 2003 model is the newest one that would be worth trading in through the government's clunkers program.

For more about Ford vehicles, go to MSN Autos.

1999 GMC Suburban 1500 SUV

The Suburban gets about 14 mpg and has about $2,300 in trade-in value. Most GMC SUVs and trucks qualify from a mileage standpoint. The newest models of the Sierra, Savana, Sonoma and Yukon still get 18 mpg or less.

For more about GMC vehicles, go to MSN Autos.

2001 Honda Odyssey LX minivan

The 2001 Odyssey would make the cut for a clunker voucher. It averages 18 mpg and less than $4,200 on trade-ins. Honda improved the van's fuel efficiency the next year.

For more about Honda vehicles, go to MSN Autos.

2003 Hyundai XG350 sedan

Hyundai typically makes pretty fuel-efficient cars. The XG350, however, was not one of them. The 2003 and 2004 XG350 models got just 18 mpg. They're ordinarily worth about $4,300 on trade-ins.

For more about Hyundai cars, go to MSN Autos.

1992 Infiniti Q45 sedan

This one-time luxury vehicle isn't so posh today. It gets just 17 mpg and is usually worth less than $550 on a trade-in, assuming it was driven an average of 12,000 miles a year. Infiniti lovers may want to opt for a G37 instead; it gets the best gas mileage of all the 2009 models.

For more about Infiniti cars, go to MSN Autos.

2001 Jeep Grand Cherokee Laredo SUV

The Grand Cherokee is one of the biggest gas guzzlers in the Jeep line. The vehicle got just 15 mpg in 2001 and would be worth about $3,500 in a trade-in. The 2009 model isn't much better: It gets 17 mpg. More-fuel-efficient Jeep models include the Patriot and the Compass.

For more on Jeep vehicles, go to MSN Autos.

2002 Kia Sedona LX minivan

Kia makes relatively fuel-efficient vehicles. The Sedona and Sorrento are two, however, that consistently are rated at 18 mpg or less. The 2002 Sedona model would probably warrant less than $1,700 in a trade-in.

For more about Kia vehicles, go to MSN Autos.

1999 Lincoln Town Car Executive sedan

The Lincoln may be the limo for overworked executives who can put car service home on their expense accounts, but older Lincolns don't warrant the luxury price tag. The 1999 Town Car, on average, would bring in less than $2,800 on a trade-in and get just 18 mpg.

For more about Lincoln vehicles, go to MSN Autos.

2003 Mercury Grand Marquis GS sedan

The Grand Marquis is similar to the Ford Crown Victoria in both style and mileage. This car gets 18 mpg and generally is worth just more than $4,300 on a trade-in.

For more about Mercury vehicles, go to MSN Autos.

1999 Nissan Pathfinder XE SUV

The Pathfinder gets about 15 mpg and nets around $2,500 on a trade-in. Unfortunately for Pathfinder fanatics, upgrading to a new Pathfinder wouldn't be possible through the cash-for-clunkers program, because the fuel efficiency hasn't improved more than 1 mpg.

For more about Nissan vehicles, go to MSN Autos.

2003 Oldsmobile Aurora sedan

The Aurora's light no longer shines so brightly. On average, the car is worth about $4,300 in a trade-in and gets only 18 mpg.

For more on Oldsmobile vehicles, go to MSN Autos.

1999 Plymouth Voyager minivan

A trade-in value of just $675 would make the Voyager well worth the trip to a dealership for new-car buyers taking advantage of the cash-for-clunkers program. The maximum government voucher would be about $3,825 more than the van's value.

Not all Voyagers would qualify, however. Only the four-speed automatic models with 3.3-liter engines or larger meet the mileage qualification.

For more on Plymouth vehicles, go to MSN Autos.

2002 Pontiac Aztek SUV

The Aztek is worth around $2,500 in good condition, so the government's vouchers would throw some more gold into the pot for owners. The vehicle gets just 18 mpg.

For more on Pontiac vehicles, go to MSN Autos.

1999 Toyota 4Runner

Nearly all 4Runner models get 18 mpg or less. The 1999 version will also give owners a hefty trade-in bonus if the clunkers bill passes. Its book value is just $3,000.

For more on Toyota vehicles, go to MSN Autos.

1999 Volkswagen EuroVan GLS minivan

Volkswagen really didn't start making gas guzzlers until the mid-2000s, when it added more SUVs to its lineup. Until then, it was all small, relatively environmentally friendly Golfs, Beetles and Jettas. The EuroVan is an exception. The 1999 model of this minivan gets just 15 mpg and, at least in some locations, is worth just under $4,500.

For more on Volkswagen vehicles, go to MSN Autos.