After Nearly Four Years on the market, Toyota Motor Corp.'s Lexus IS sport sedan has garnered much attention for the brand from consumers and reviewers alike, including Ward's, which has honored the car's 306-hp 3.5L V-6 as a 10 Best Engine for four years running.

But sales of 49,432 vehicles last year still lag those of Lexus' luxury arch-nemesis, BMW AG, and its 3-Series, which sold 112,464 units in 2008.

For those who were expecting driving performance on par with the 3-Series or 4-door IS, the IS-C convertible is underwhelming. It is heftier than its 4-door brother, which translates into a plusher ride likely to attract an older buyer.

Unlike the lightning-quick reflexes of the IS sedan, the IS-C, due to all the body reinforcements, is a soft-roader in comparison, wallowing through curves and not transmitting as much road feel into the cabin.

The convertible gains 300 lbs. (137 kg) due to the roof and extension of the IS sedan platform. Ward's tested all three variants of the IS-C recently: the IS 250C with both manual and automatic transmissions and the IS 350C.

The direct- and indirect-injected 3.5L V-6 of the IS 350 remains one of the best sixes available today, providing just the right level of power for comfort cruising while allowing the driver to unleash a wicked 277 lb.-ft. (376 Nm) of torque.

Aggressive tip-in of the throttle makes for loads of fun. The 2.5L V-6's 204 hp is adequate, as it is in the sedan.

As with the sedan, the only gearbox choice for the IS 350C is a 6-speed automatic transmission. The 2.5L version is mated to either a different 6-speed automatic or 6-speed manual.

After four years, the manual transmission doesn't stack up well against more crisply shifting European competitors. However, the IS 250C's clutch is much more pliable than the tightly sprung clutch of the Infiniti G37. Both 6-speed automatics have paddle shifting.

Lexus says the Environmental Protection Agency estimates IS 250C fuel economy at 21/29 mpg (11.2-8.1 L/100 km) city/highway and the IS 350C, 18/25 mpg (13.1-9.4 L/100 km).

Ward's got 19.4 mpg (12.1 L/100 km) on a 24.5-mile (39.4-km) route in the IS 350C; 21.5 mpg (11 L/100 km) on a 22.8-mile (36.7-km) trip in the IS 250C with the automatic; and 23.7 mpg (10.9 L/100 km) over 6.7 miles (11 km) in the IS 250C with the manual transmission. Most of the routes had low to middle speeds, with only a slight portion of freeway driving.

The centerpiece of the IS-C is its retractable hardtop. Developed by Toyota, it opens and closes in 20 seconds, activated by a button near the steering wheel.

To accommodate the massive, 3-piece roof, Lexus engineers tinkered with the sedan's proportions. The resulting exterior is a bit ungainly: the IS-C has a lot of junk in its trunk, and we're not referring to golf clubs.

The lack of another side door also results in a very slab-sided appearance for the IS-C. A character line below the door handle would add visual interest.

Inside, the IS-C has the same interior as the sedan. It lacks the superior materials and newer switchgear of the Lexus '10 RX and '10 HS hybrid sedan, but nevertheless boasts the brand's hallmark fit and finish.

A 2-tone leather interior of blue/alabaster — more of a navy/ivory — is very eye-catching and fresh, giving buyers something different than the orange-colored saddle leather popular now.

Getting in and out of the IS-C's back seat can be difficult without the optional single-touch rear access function offered in a luxury package. Otherwise, a one-leg-out exit is necessary, especially if the IS-C's roof is up.

But the back seats are large, thanks to the extra 2.25 ins. (5.7 cm) added to the convertible to accommodate the roof and spacious trunk.

On the technology front, the convertible's climate control system compensates for sunlight when the roof is open by adjusting airflow and temperature, and the audio system has an equalizer that “maintains the current acoustic field” for roof open or closed situations.

Three option packages are available, but all will set buyers back more than $3,000, with the navigation package alone costing nearly $4,000, something to keep in mind as Lexus touts the IS-C's sub-$40,000 starting price.

Lexus is offering its F-Sport line of accessories on the car, which includes lower springs and shocks, sway bars, sport-shift kit and large, high-performance brake rotors. If selecting the latter choice, optional 19-in. wheels will be necessary, Lexus officials say.

Of the non-F-Sport accessories, a $650 windscreen, which can be stored in the trunk, seems particularly useful.

Lexus sees buyer demographics for the IS-C mimicking those of other luxury convertibles: 50/50 male/female and an average age of late 40s to early 50s, The auto maker expects sales of 1,000 units a month, noting one-third of 3-Series sales are of the convertible.

But in this economic environment, drop-top sales have taken a beating, and 500 deliveries per month seems a more realistic goal.

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'10 Lexus IS 350C

Vehicle type: Front-engine, rear-wheel-drive, 2-door, 4-passenger convertible

Engine: DOHC 3.5L V-6 with aluminum head, block

Power (SAE net): 306 hp @ 6,400 rpm

Torque: 277 lb.-ft. (187 Nm) @ 4,800 rpm

Transmission: 6-speed electronically controlled automatic with paddle shifters

Wheelbase: 107.5 ins. (273 cm)

Overall length: 182.5 ins. (464 cm)

Curb weight: 3,880 lbs. (1,760 kg)

Base price range: $43,940, plus $875 destination and handling

EPA mileage: 18/25 city/hwy (13.1/9.4 L/100 km)

Market competition: BMW 3-Series, Infiniti G37