It’s the Holy Grail of the current alternative fuel vehicle, according to its would-be importers—a full-function, freeway-capable five-passenger sedan that runs on electricity alone.

The latest company to promise the vehicle is Miles Electric Vehicles, a Santa Monica, CA-based company that is planning to bring such a Chinese-built EV to the U.S. market by the end of 2009. The arrival time for the XS500, which the company says will be the first affordable, all-electric highway sedan, was confirmed in a HybridCars.com interview with the company’s COO at the Green California Summit & Exposition where Miles was a “Gold” sponsor (second only to the top-level “Platinum”). It has been pushed back from an early estimate of 2008.

COO Jeff Boyd said the car, which will cost “in the $35,000 to $39,000 range,” has been delayed as safety equipment is added and certified—to bring the vehicle up to the safety levels mandated in the United States. Boyd said it costs a company $6 million to add current spec airbags to the XS500—alluding to but not mentioning Tesla Motors dodge of that cost by applying for a waiver to introduce their EV with older-version airbags. He said he expects to sell 18,000 to 30,000 units of the car the first year through a 70-dealer network, focusing on fleet sales that the company has pioneered with its low-speed vehicles.

The Miles XS500 is battery electric four-door sedan. According to Miles Electric Vehicles, the Miles XS500 can travel at a maximum speed of 80 miles per hour, and achieve a range of more than 120 miles. The body of the vehicle was designed by Pininfarina, the legendary Italian car design house.

The bottom line is bringing an EV to the U.S. is a complicated an expensive task; Miles seems to be moving forward, but at a slower pace than anticipated with costs, and the final purchase price, coming in higher than anticipated.