The white, rectangular building at 6369 N. Green Bay Ave. has a history of providing fuel for the bustling Glendale neighborhood. For years, it was a neighborhood gas station, but earlier this year, Bob Olin and his family converted the space to another kind of fuel outlet: a coffee shop.

Kletzsch Perk, similar in name to Central Perk on "Friends," is the sister cafe to Olin's Sherman Perk, 4924 Roosevelt Dr. Sherman Perk, which opened a few years ago, is also located inside a retro-fitted gas station and is Wisconsin's only kosher coffee shop.

Although Kletzsch Perk experienced a slow start due to road construction this summer, business is steadily improving. Cafe manager Missy Kral, who is Olin's sister, barely has time for the interview in between making cappuccinos and serving fresh croissants to customers, many of whom she knows by name.

"This is what we wanted," says Kral, who lives in Whitefish Bay. "To bring a community coffee shop to the Glendale area."

Kletzch Perk serves Alterra coffee and whips up all of the usual coffee treats: cappuccinos, lattes, mochas and espressos. They also offers hot chocolate and chai.

Because the building is only 1,200 sq. ft., Olin could not set up a proper food preparation site. Instead, fresh sandwiches are delivered daily from Subway and breakfast items are imported from La Bou, City Market and La Parve. Knorr soups are also available.

Prices are average, with cappuccinos and chais running between $2.75-$3.75 and regular cups of coffee going for $1.25-$2. Subway sandwiches are fairly marked-up from their original price.

Both of "The Perks" are completely non-smoking. Sherman Perk currently features weekly music and poetry nights, and after the holidays, Kral plans to start Friday night music events at Kletzsch Perk as well.

Both cafes are run almost entirely by family. Kral works with her (and Olin's) mother every morning, and three of her four children also take shifts. "We only have three people on the staff that aren't immediate family," says Kral. "But they're like family anyway."

The comfortable cafes have an air of genuine friendliness, and welcome java drinkers of all ages. On a Monday afternoon, a college-aged woman reads a novel in an overstuffed chair while two senior citizens sip coffee at the counter overlooking Green Bay Avenue.

Both java joints are simple and clean. Kletzsch Perk is especially sharp with freshly painted white walls and red trim with retro red stools to match.

"Both of our cafes have a 'come in, sit down, how are you doing?' sort of feel," says Kral. "It's a really nice thing, and a fun thing, to be doing."

Kletzsch Perk and Sherman Perk are open Monday-Friday, from 6:30 a.m. to 6 p.m., Saturday from 7 a.m. to 4 p.m. and Sundays from 8 a.m. to 2 p.m.