When a perfect Porsche isn't good enough

(Fortune Magazine) -- Most drivers see a top-of-the-line Porsche or Mercedes as a finished product. But a small handful of independent builders see those already great car platforms as a canvas for custom bodywork, upgraded interiors, and enhanced performance.

Such masterpieces are usually low in volume and extremely high in man-hours and cost; only the best survive. In many respects, the ne plus ultra is Germany's Ruf (see Outrageously cool custom-built cars), a company that has improved upon already benchmark Porsches for four decades.

Henrik Fisker restyled the Mercedes SL inside and out to create the Fisker Tramonto.

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(In the interest of full disclosure, my husband, Reeves Callaway, has been building breathtakingly fast and beautiful cars based on the Corvette for 20 years.)

One of the more recent entrants to this field is taking a slightly different approach: Henrik Fisker, founder of Fisker Coachbuild. Formerly Aston Martin's chief designer, and before that the CEO of BMW's Designworks/USA, Fisker overhauls the exteriors and interiors of the Mercedes SL and BMW M6 to create two models, the Tramonto two-seater and the Latigo CS coupe.

Unlike other companies, Fisker has stayed true to the tradition of classic coach-building by outsourcing the performance upgrade work and focusing on the touchpoints.

"Our customers are connoisseurs who appreciate fine detailing and materials," says Fisker. To that end, he offers -- gasp! -- completely natural, untreated leather that is glove soft; classic hand-milled aluminum details, polished carbon fiber, and unique LED taillights.

Fisker just announced that he will also create his own high-performance plug-in hybrid sedan. He'll show a prototype next January in Detroit and have the sedan ready for sale within 18 months -- well ahead of any major car company.

Using his own vehicles as the basis for custom coachwork should make such status symbols deliciously cost-effective. Prices for Tramonto and Latigo CS range from $199,000 to $369,500, including base car. Hybrid pricing will be around $80,000.