Mazda North American Operations forecasts 25% of ’07 Mazda MX-5 buyers will opt for the new power retractable hardtop (PRHT) model that hits U.S. dealerships later this month.

Mazda took its time developing the vehicle, the first MX-5 Miata with a power hardtop, not wanting to detract from the MX-5’s distinctive styling and exceptional performance, a spokesman says.

“The challenge for the engineering group (was) to maintain all of the attributes of the MX-5 Miata, which are light weight, affordability and fun to drive,” he says. “To their credit, the Mazda engineering group in Japan delivered on that, so the car looks as good with the top up as it does down.”

The optional hardtop, supplied by Webasto AG, carries a $1,850 premium and adds 77 lbs. (35 kg) to the base Miata. The tops are installed in Japan before the cars are shipped to the U.S.

The ’07 MX-5 Miata with PRHT will base at $24,350, not including destination charge.

MX-5 Miata sales have been on a tear this year, posting a 107.6% increase through October on 14,878 units. The auto maker could sell more than its projected number of MX-5 PRHTs, but is limited by supply, he says.

Overall, Mazda expects to sell 16,000-17,000 MX-5s in the U.S. this year.

“Demand will probably outstrip supply,” the spokesman says. “Right now we’re looking at 20%-30% of the supply, and chances are we’ll meet or exceed that, no problem.”

Mazda engineers made a few modifications to accommodate the hardtop, including replacing the original aluminum convex trunk lid with a steel version.

“This retractable hardtop resides in exactly the same area as the soft top, therefore it takes up no trunk space,” the spokesman says. “In fact, the trunk is 3% bigger because the truck lid is a little higher.”

Other modifications include stiffer springs, different dampers and a larger diameter front roll bar. Additional steel was added to the bumpers, and the rear window was expanded.

The hardtop takes only 12 seconds to be raised or lowered, making it twice as fast as the next closest competitor, the spokesman says.

“People will come in (to dealership) and see a car that has a top that goes up and down in 12 seconds and adds very little to the price tag and say, ‘Yeah, this is the car I want,’” the spokesman says.

Mazda says the MX-5 PRHT will satisfy customers who have asked for the option for “security reasons and quietness.”

A test conducted by Edmunds.com revealed that at 70 mph (113 km/h), noise levels in the hardtop MX-5 are reduced to 70 db, compared with 72.9 db for the soft top version, Mazda says.

“It’s a substantial reduction, but it’s still very much a roadster,” the spokesman says.

As with the soft top MX-5, Mazda expects men to account for 52% of hardtop sales.

bpope@wardsauto.com