I'm calling a bottom: The abysmal pace of U.S. auto sales - a massive downturn that's lasted for 18 months - seems to be at a turning point. That could be mighty good news for drivers who have to replace their old cars.

Here's why: You want to scoop up a new vehicle before dealer inventories (the supply on hand ) shrink so much that the big discounts fade away. These incentives may include "employee pricing" close to invoice price, dealer coupons, "owner loyalty" discounts, factory cash to the buyer, even 0 percent financing for 60 months.

Experienced investors try to scoop up bargain-priced stocks before other buyers realize a market upturn has begun. Tighter auto inventories were seen in June sales reports. And because auto production has been cut, dealer and factory incentives likely will fade by the end of summer.

- 'Cash-for-clunkers' program not a panacea. Auto sales could get an adrenaline boost in late July as owners of certain older vehicles take advantage of the "cash for clunkers" program Congress approved three weeks ago. Buyers can get a voucher worth up to $4,500 by trading a gas guzzler for a new, more energy-efficient model.

Through November, this $1 billion program will give dealers access to "electronic vouchers" that buyers can use to purchase or lease qualifying vehicles. To qualify for a $4,500 voucher, the new vehicle must get at least 10 mpg better mileage than the clunker. A new model that gets 4 mpg more than the trade-in will qualify for a $3,500 voucher. All clunkers will be crushed.

The program limits trade-ins to models that are 1984 or newer, and get less than 18 miles a gallon. See how the government calculates these vouchers at www.fueleconomy.gov.

This program probably makes no sense if your older car is worth more than $4,500, is somewhat fuel efficient, has an odometer reading of 50,000 miles or less, is dependable and doesn't need major repairs. One key question: If the vehicle were decimated by a tornado, would $4,500 buy you a comparable replacement? No? Keep the vehicle.

- New car purchase lets you write off the sales tax. A separate tax break in last spring's federal stimulus plan might help in your junk-the-clunker decision: Purchasing a new car, light truck, motor home or motorcycle between Feb. 17 and the end of this year allows a write off of the sales tax - even if you don't itemize - on your 2009 tax return.

- Calculate, compare the five-year costs. Still not comfortable trading into a new vehicle? Take a five-year look into the future.

Web sites such as Edmunds.com can help you compare the total ownership costs of hanging on to a vehicle (one that's paid off) with upgrading. Five-year costs would include any financing for the new vehicle, plus estimated maintenance, repairs, insurance and fuel. Don't forget depreciation. A new car loses a third of its value the day you drive it off the dealer's lot.

If you have a Lessons Learned topic to suggest, you can call Gene Kelly at 421-2861, write to him at 2611 Bretigne Circle, Lincoln, NE 68512, or e-mail him at EKELLY1@neb.rr.com.