Movie buffs might recall that Albert Finney and Audrey Hepburn had an early 1950s MG TD sports car when the bittersweet 1967 movie "Two for the Road" began, and ended up an affluent, seasoned married couple in a Mercedes-Benz 250SL roadster.

The 250SL sat in the middle of Mercedes' phenomenally successful 230SL-to-280SL model series. The cars were built from 1963 to 1971 and still are a fairly common sight.

The 230SL replaced the Mercedes 300SL and 190SL convertibles of the mid-1950s and early 1960s. It had the 190SL's handy size but was virtually all-new. It also was the last Mercedes two-seater that lived up to its "SL" (Super Light) designation.

The reasonably priced 190SL was a pleasant, stylish two-seat cruiser that easily outsold the costly 300SL, which was an all-out sports car. Mercedes decided to go for volume with its new two-seater, and thus made the 230SL affordable, at least to upper-middle-class folks. To hold costs down, it used parts from conventional Mercedes sedans, which were nicely engineered.

The crisply styled 1963-71 SL convertibles had timeless grace and were regarded as luxurious "sports-touring" cars, not hard-edged sports cars. They looked the same, with square-cut lines, flared wheel arches, vertical headlight pods and a low "SL" grille with the three-pointed star Mercedes emblem.

One of the few ways you can tell one from another is to read the trunk lid badging. For instance, the 280SL had a small, chromed "280 SL" trunklid insignia and small side marker lights on its fenders.

The 230SL was immediately popular in America, partly because it was the first sporty Mercedes offered with an automatic transmission -- a new four-speed unit. A four-speed manual gearbox was standard.

The soft top folded from sight beneath a cover, and the car's square lines allowed more trunk space than in previous SL models. The new SL also was offered with a distinctive, optional removable steel hard top. It had a depressed center section that led it to be called a "pagoda" roof.

The stylish roofline curved upward at the sides to increase rigidity and glass area. The roof was the talk of the 1963 Geneva, Switzerland, auto show, where the 230SL was introduced. But Mercedes meant the roof to be purposeful, not controversial, because every major item it put on cars was strictly functional.

The leather-swathed interior had large, comfortable, reclining seats and the usual Mercedes dashboard layout, with a large speedometer and tachometer and smaller gauges. It also had windows-up fresh-air ventilation and one of the industry's first multipurpose control stalks for lights and wipers.

A small rear package shelf allowed seating for two children during short trips.

The 1963-66 230SL was renamed the 250SL for 1966-1967 when its fuel-injected 2.3-liter, 170-horsepower overhead camshaft six-cylinder engine was enlarged to 2.5 liters. The move was needed to counter the car's higher weight, caused by U.S.-mandated safety equipment and tougher emissions standards. Horsepower was unchanged, but torque was increased for better response and refinement.

The 250SL was short-lived because the SL needed an even larger 2.8-liter six with 180 horsepower and added torque to meet even stricter U.S. standards. It thus was called the 280SL from 1968 to 1971, when replaced by a new V-8 two-seater. The new Mercedes was larger, heavier and costlier. It also looked bulkier.

The 1963-71 SL was lively. A 230SL hit 100 mph in 27 seconds, which wasn't quick by Corvette standards but was still fairly fast. That SL won Europe's tough, prestigious Spa-Sofia-Liege rally in its first year, and SLs went on to take several rally wins because they were strong and quick.

Well-known auto writer Bernard Cahier called the 230SL "one of [Mercedes'] finest cars."

Besides its larger, stronger engine, the 250SL got better seat belts and disc brakes at all wheels, instead of just discs up front.

The 280SL's federally mandated features included an energy-absorbing steering column and side marker lights. You now could get an optional five-speed manual transmission, although the automatic was the SL's most popular transmission in America.

The 1963-71 SL models found 48,912 buyers. The 280SL was the most popular version, with 23,885 sold.

A 230SL in excellent condition is valued at $19,000, while a 250SL is worth $19,250 and a 280SL goes up to $29,500. They're easily worth the money.