They don't need to immediately replace them. Russia has lost about a hundred tanks. They have nearly 13,000. They've lost about a dozen Su-27s, they have about 500.
And I'm a little more afraid for Ukraine having seen those civilian cars. It feels like Russia is going to start playing very dirty during the upcoming siege of Kiev. It sort of evens the playing field if the defenders also have to watch their backs everytime an unmarked civilian car drives by. It's a dirty move right out of Russia's playbook.
In the videos I saw, the cars were marked with the "Z". So at least for those particular vehicles, dirty tricks may be out of the question.
One other possible advantage is that Ukraine soldiers might be reluctant to fire anti-tank missiles at civilian vehicles from long range (I assume that the markings would be hard to see from that distance). And the missiles might cost more than the vehicles themselves, so might be a waste regardless. Small arms fire would probably be sufficient to stop the vehicles, but that would have to happen at closer range. So maybe the idea is that they can get in closer to the engagement point before receiving fire. Also, they can probably move faster and use less fuel, which considering their logistic challenges might actually be the main motivation.
So yeah, I could see this being strategic and not a desperation move. But either way, not the best look for their military. Hard to justify all of that spending on advanced hardware if at the end of the day they end up using civilian vehicles.
You can repaint a car about as easily as you can put a Z on it. And the Z on the train means that a conscript doesn't take lot shots at it just because they missed that the first few cars had a Z on them.
How many of those 13 000 tanks and 500 Su-27s are in deployable condition?
The former Soviet Union was excellent in production of impressive statistics, but the reality on the ground didn't quite match. And the Soviet way of thinking is very much alive in Putin's power circles. It is cheaper to produce impressive numbers than to actually take good care of equipment, and some people will swallow those numbers without thinking twice.
Westerners from well-run countries tend to trust government figures. This may work in Sweden or even in the USA, but in case of Russia, consider every published statistics as suspect.
And I'm a little more afraid for Ukraine having seen those civilian cars. It feels like Russia is going to start playing very dirty during the upcoming siege of Kiev. It sort of evens the playing field if the defenders also have to watch their backs everytime an unmarked civilian car drives by. It's a dirty move right out of Russia's playbook.