The story of Milwaukee band Hudson begins with an old postal truck.

When Paul Jonas returned from studying in Germany in the mid-'90s, he bought a mail Jeep, and to his amusement, the vehicle's keys were inscribed with the word "Hudson." Naturally, Jonas nicknamed the truck Hudson, and later, when he decided to start a '60s organ-based trio, he dubbed the group with the same name.

Jonas' original vision was to form an instrumental trio able to serve as the rhythm section for any genre of music, giving him the freedom to explore a variety of styles. He recruited drummer Matt Liban and keyboard player Matt Meixner, both former members of the Willy Porter Band, and the three started creating extended jazz-fusion jams peppered with rock, country and blues.

Eventually, they recorded a 12-song CD, "On," with guitarist Bryan Mir and producer Jeff Hamilton, but it only scratched the surface of Jonas' long-term goals. Their second album, due out next spring, will include vocal tracks and more of a rock 'n' roll flavor, but will remain committed to their infamous on-stage improv.

The five-song demo CD -- later to be expanded into the second record -- is tentatively called "Hudsongs" and teases listeners with the band's potential to produce an explosive sophomore effort. The addition of Jonas' vocals intensifies the banter between a variety of moods, from the soulful and melancholy ballad "Always" to the throaty and commanding blues tune "Nikki."

"This (new) recording will appeal to a lot more people," says Jonas, 36, who played with Helena Handbasket from the early-to-mid '90s. "I've noticed instrumental music cuts out 80 percent of the population. No matter how good you are, you're still only getting 20 percent of the pie."

The trio recruited the talents of guitarists Chris Tishler and Jeff Benske to help pioneer the band's new path. The fivesome also perform together in the retro lounge band, 5 Card Studs.

Because the band members have so many other music projects (Jonas also plays with Sunny Gets Blue; Meixner sits in with The Probers; and Liban drums for Goran Kralj of The Gufs), Jonas claims he became the leader by default. But it's a role he puts a lot of energy into, including the writing of every song on the new album.

Jonas believes the band's commitment to alternative/straightforward rock will open doors to clubs they haven't played before. "The Nomad has always been our home base, and Onopa is great ... but now we have enough of an edge for The Cactus Club," says Jonas, who predicts the band will play out at least once a month starting this fall.

Local musicians sometimes complain about the poor attendance at Milwaukee shows, but Jonas has a different perspective and a good attitude towards his upcoming rigorous performance schedule. "It's more a matter of grabbing a hold of the listeners who are there rather than wishing ten times as many people had come out," he says. "Take advantage of who's there instead of ruing over the fact there aren't more."

Although Jonas doesn't have Hudson the postal Jeep anymore (he decided to give it away after leaving it abandoned behind his Mitchell Street studio and homeless people not only moved into it but started relieving themselves next to it) he hopes Hudson the band will accelerate to a new level.

Hudson will play an acoustic show on Thurs., Aug. 21 at the BBC and a plugged-in show on Fri., Sept. 5 at the Ale House. Jonas, Meixner and Liban also play every Sunday evening until the end of September at Trocadero from 6 to 9 p.m.