IT WAS THROWBACK time, time to let go, hang loose, put on some floppy pants and a faded shirt and hit the road. The car was the 1990 Ford Mustang GT convertible -- perfect for the day, which was clear and beautiful, and for the occasion, which was nothing at all.

I lowered the top, forgetting the manufacturer's instructions to first unzip the rear window. But the vinyl roof and plate glass window fell into place without a hitch or scratch. I cranked the engine.

The five-liter V-8 roared. Oh, it was a mighty roar, too -- loud and lusty enough to make an environmentalist curse -- which brings up a point.

The Mustang, now in its 25th year of production, is the last of a breed. It is an unabashed, big-muscled brute of a car weighing 3,327 lbs. and pumping 225 horsepower at full howl. It is a wild thing -- a relic of an age when Americans still enjoyed the illusion of self-determination, a shining reminder of bygone days when a little hell could be raised without raising the ire of Responsible Citizens for This and That.

Frankly, that's why I still love the Mustang. It's yesterday's news in terms of technology. But it symbolizes what America and personal mobility are supposed to be about -- freedom, and the unmitigated joy of movement.

Background: The Ford Mustang was introduced in April 1964 as a 1965 model, the first of America's legendary "pony cars." It came in several forms, first as a long-hooded, notchback coupe with a relatively tame six-cylinder engine and automatic transmission, and later as a fastback and a convertible.

Introduced at an original base price of $2,480, Ford sold an astounding 500,000 Mustangs in the first 18 months of the car's life, according to auto historian Leon Mandel.

A good 1965 Mustang today is worth a tad more than its original price. A fastback is worth twice as much, and an early Mustang convertible in good condition can fetch five times what it cost new -- nearly $15,000, Mandel said.

The 1990 Mustangs include the GT and LX convertibles and hardtops, with the GTs being the most expensive models.

Mustangs traditionally have been rear-wheel-drive cars and remain so today. The new Mustangs have standard driver's-side air bags.

Complaints: In future Mustangs, assuming that the company continues the line, Ford ought to find another place to put the fuse box. The thing gets in the way of the left foot in its current driver's-side position underneath the dashboard.

Wet-road handling also needs to be improved in this car.

Praise: The original Mustang was a celebration of youth and freedom. The 1990 Mustang GT convertible, though dated in comparison to a host of new competitors, continues the party. The GT is somewhat fat and noisy, whereas its latest rivals are trim, prim and cute. But when it gets down to highway boogie, the GT can still show the new rides a thing or two.

Head-turning quotient: A car that proves that fat can be downright sexy.

Ride, acceleration and handling: The Mustang GT convertible is tight -- no discernible shakes or rattles to upset your cruise. Dry-road handling is superior. Wet-road handling at high speeds can make you reconsider the course of your life. Do not -- repeat -- do not go zipping around slippery curves in this one. It will spin out. Speeding on wet curves is dumb anyway.

Sound system: AM/FM stereo radio and cassette by Ford Premium. Excellent.

Mileage: A wanton 17 miles per gallon (15.4-gallon tank, estimated 25-mile range on usable volume), running mostly highway and driver only with top down.

Price: Base price is $18,805 on the tested GT convertible with standard five-speed manual transmission. Dealer's invoice price on that model is $16,921. Price as tested is $20,008, including $783 in options and a $420 destination charge.

Purse-strings note: You buy the GT convertible with your heart instead of your mind. If you can afford that kind of passion, go for it.

Warren Brown covers the automotive industry for The Washington Post.