Fashion calls it a diffusion line, the music industry has (or had) B-sides, sports leagues play reserves: could the hybrid bar-restaurant so popular in Melbourne today be hospitality’s equivalent?

Created by established high-end restaurants, this increasingly popular class of venue lets diners have the best of both worlds. Want a great bottle of champagne to go with six oysters? Or a “snack-ustation” for dinner, instead of the chef’s three-hour tasting menu? Head to your nearest fancy bar.

Often located next door, upstairs or down the street from their older sibling, they’re the micro version of your favourite restaurant: more intimate, less of a commitment and with a smaller bill.

Ides in Collingwood and Navi in Yarraville – both two-hatted restaurants – have spilled into neighbouring shops and created plush bars in the last three years. Then, Shane Delia added Jayda next door to his flagship city restaurant Maha. This year, Mister Bianco restaurant in Kew, Scopri in Carlton, Rumi in Brunswick East, Enter Via Laundry in Carlton North and Hopper Joint in Prahran are all doing the same.

In each case, these spin-off bars have their own menus, entrances, atmosphere, booking policy and, in many cases, identities.

Rumi, which has 17 years’ worth of loyal regulars, added The Rocket Society bar when it relocated in December. The second venue allows its team to create new dishes – including $8 wraps at lunchtime – without messing with the Rumi menu that guests are so attached to.

At Bianchetto, the neighbouring bar to Kew’s Mister Bianco, no dish costs more than $15, and there are more desserts than is typical for a bar. With its inky interiors and curtained windows, it’s pitched as a nightcap destination.

Lots of restaurants have bars within them: places you can have a drink while you wait for your table, or perhaps stay all night and order from the main menu. And there are dozens of wine bars in Melbourne. These spots are another breed.

There’s no clearly defined name. Are they the fine-diner bar, the resto-bar, the low-commitment restaurant, or the fun younger sibling? Perhaps the best way to think of these venues is as a low-maintenance and, importantly, affordable best friend.

With cost of living the phrase on everyone’s lips and restaurants beginning to shut their doors as customers stay home, it’s obvious why restaurants would want more affordable propositions for their guests.

Some operators say the rise of the bar is less about the economy and more directed by diner preferences.

“It’s a really fun way to dine,” says Anthony Scutella, owner of longstanding favourite Scopri, which is opening a standalone bar called Bar Olo this month.

“It’s slightly more laid back … A restaurant commitment is a big night out sometimes, but it doesn’t need to be that involved.”

Visitors to Navi Lounge, next door to Yarraville fine diner Navi, liked the bar’s flexibility so much that they used it more like a restaurant and settled in for the night. So, chef-owner Julian Hills introduced more substantial dishes that could become dinner.

Visiting a fine-diner’s bar can also be a gateway to making a reservation at the restaurant, a way to try before you buy, so to speak.

Hills says some diners at Navi have visited Navi Lounge six or seven times before. He is careful to keep everything at the bar on par with the restaurant’s standards.

Helly Raichura of Enter Via Laundry, which only serves tasting menus but this week added a bar, agrees that quality is paramount.

“Even though you’re coming in for a little bit of this and a little bit of that, I don’t want [guests] to feel that it’s been thrown together. It’s all thought through,” she says.

The format may not work for people who see dinner as a square meal of meat and three veg. And at some venues, the emphasis on quality can add up, whether it’s $27 cocktails, or seafood dishes for $32. But it’s a formula that appeals to some, with Navi Lounge continuing to see weekly and monthly regulars three years after opening.

Melbourne’s most noteworthy restaurant bars

Bar Jayda (next to Maha), 19 Bond Street, Melbourne, barjayda.com.au

Bar Olo (owned by Scopri), 165 Nicholson Street, Carlton (opens later in April)

Bianchetto (next to Mister Bianco), 26-28 Cotham Road, Kew, misterbianco.com.au

Enter Via Laundry’s bar, 507 Nicholson Street, Carlton North, entervialaundry.com.au

March (next to Ides), 92 Smith Street, Collingwood, idesmelbourne.com.au

Navi Lounge (next to Navi), 3A-83B Gamon Street, Yaraville, restaurantnavi.com.au

Rocket Society (next to Rumi), 2 Village Avenue, Brunswick East, therocketsociety.com.au