Mr Ahmad Attaie stands in the middle of a busy auto shop holding what resembles a bent wire coat hanger attached to a small cube that looks like a Lego building block. He is developing an inexpensive turn signal, which should cost about 75 US cents (95 Singapore cents).

The turn signal will go into the SGT01, the car being developed by Wikispeed, a unique car company in Lynnwood, a Seattle suburb.

The SGT01 will cost US$25,000, get 46.3km a litre, and will be infinitely customisable - an eco-friendly, affordable car manufactured using computer software as a prototype instead of an assembly line's methods.

Its parts will be inexpensive - like Mr Attaie's turn signal - and quickly interchangeable. (Wiki means quick or fast in Hawaiian.)

For example, its owner can change its fuel system from petroleum to ethanol to electricity at minimal cost and with a short visit to the shop.

The goal of not-for-profit and volunteer-run Wikispeed is to solve problems rapidly for social good, and the car is its most high-profile project.

Mr Joe Justice, its founder, entered his first Wikispeed SGT01 in the 2008 Progressive Insurance Automotive X Competition. It placed 10th, but remains the only entry that has been developed for sale.

The car sits long and low, looking like a go-cart built by children for a soap-box derby.

Every car will be unique, says Mr Justice, and won't look like the one in the shop.

This model is a race car. Another model might seat four and have a boot. Buyers can change their minds and change the body style as they want.

Five Wikispeed cars have been sold.

At the shop, the busy volunteers include Mr Attaie, an electrical engineer, a software engineer, a former teacher and several students.

Part of Wikispeed's innovation is in its "agile" approach, which allows staff members to choose a task that uses their skills best.

Said Mr Rob Beresford, a former teacher: "People do a better job when they choose their own tasks."