Marussia and Caterham are Formula One's "new teams."
Despite both now being well-established, they retain this title because neither has managed to make the transition from new-on-the-block backmarker to midfield runner.
But Marussia and Caterham started out last, and are still last.
Is their time running out?
Marussia have been in Formula One since the start of the 2011 season. Their entry began life as Virgin Racing, before the Russian sports car company bought a controlling stake in the team at the end of the 2010 season.
It was renamed Virgin Marussia for 2011, and the full Marussia re-brand was completed in time for 2012.
Since their debut, Marussia have competed in 70 races and scored just two points—both by Jules Bianchi at the 2014 Monaco Grand Prix. It was a first-class drive, but points would have been out of the question had so many others not hit trouble.
Caterham dwell in a similar boat. The team founded by Malaysian businessman Tony Fernandes began racing at the start of 2010, calling themselves Lotus. In 2012 they switched to their current name.
They have tended to aim higher and have always had a slightly larger budget than Marussia, but they too have struggled for results.
From 89 starts, the team have a grand total of zero points.
Neither team has been anywhere near a Top 10 finish on pace alone, and in any normal qualifying session, they will occupy the rear two rows of the grid.
And neither has shown any sign of being able to improve any time soon.
F1 is an arena in which money leads to success, which in turn leads to more money and more success.
Teams at the top of the constructors' championship—who typically have larger budgets to begin with, courtesy of their owners—receive a much greater share of the prize fund than those at the bottom. This helps them maintain their position at the front of the field.
They can afford the best drivers, engineers and other technical staff, and can spend far more on researching and developing their cars. This (usually) gives them a substantial performance advantage
In addition, certain teams receive a benefit from historic or current success in the form of additional payments for their "importance" to the sport.
The smaller fish have lower budgets to begin with, don't get "thanks for coming" bonuses and, because they tend to finish lower in the championship, receive less of the prize pot.
They can't afford the best drivers and have less to spend on their cars. They're also unattractive to the best sponsors, who have little interest in being associated with failure.
The vicious circle remains intact, and they remain rooted firmly in the bottom half of the field, struggling to raise enough cash to stay afloat.
It's hard enough for teams like Force India and Sauber, who occasionally produce a solid result and are (usually) regular points-scorers.
For true back-markers like Marussia and Caterham, it's an even greater problem. They can't even attract the "good" pay-drivers—they have to settle for lower amounts, often from lesser talents.
It's never enough.
Putting two cars on the grid and making them quick enough to be halfway competitive costs more than such teams will ever receive from sponsorship and prize money.
Their owners have to stump up the difference—and they can't continue to do so indefinitely.
In an ideal world, Marussia and Caterham would each attract a wealthy benefactor or partner, willing to pump hundreds of millions into the team to propel them up the grid.
This would lead to better results, more prize money and greater appeal to sponsors—the vicious circle would become a happy, smiley one.
But if they continue in their current state, they're not going to last.
Without any success or hint that it might be around the corner, those funding the teams will sooner or later come to the conclusion that there's no point carrying on.
Tony Fernandes did just that, and without a last-minute rescue by the Colin Kolles-advised group of investors, Caterham might have folded back in July.
If they don't improve, do you WANT to see Marussia and Caterham in F1 beyond 2016?
Even now, they are resorting to selling their best driver's seat on a race-by-race basis to raise additional funds. That's no way to go racing at the top level.
Marussia's situation is perhaps even more perilous. As reported by Wroom.ru, the company after which they're named—Marussia Motors—closed its doors and shut down earlier this year.
If they were doing well, there'd be every reason to keep the F1 team going. But what's the point of an unsuccessful, unprofitable F1 entry set up to promote a company that no longer exists as a trading entity?
The entire reason for the team being there has gone.
If new, wealthier owners come in for Marussia, and the new team in charge of Caterham injects some serious money, both could continue in the sport for many years to come.
But without success—at the very least occasional points and regular departures from the back rows of the grid—there's little reason for either to still be around by the end of 2016.