It's fun to read threads about the Vega. Very much like reading Fram oil filter threads
I bought a '72 GT in about 1976. 26,000 miles. Not a high-tech car, but compared to the air-cooled VW stuff I'd been driving for years I can testify the Vega's engine power, heating, a/c, and some crosswind resistance were all wonderful compared to VWs.
One cold South Dakota day (is there any other kind?) the better half hit a small, rock-hard snow drift while driving at highway speed. Yes, small drifts can be surprisingly hard. The car bounced high enough that the resulting landing compressed the engine mounts enough to drag the oil pan on the pavement and tear it open. Naturally, the engine seized a few miles later (the switch that should have shut off the electric fuel pump upon the loss of oil pressure obviously didn't work). We towed the car home; when I dropped the pan I discovered the heat and pressures that resulted from the oil loss caused the bearing shells to melt and flow out along the journals. As a college student with no money, I threw in a set of new bearings and called it good. Things were fine for the next several thousand miles until one day I forgot about the repairs and made a trip driving way too fast. As could be expected, some knocking noises followed shortly thereafter. Nothing ventured, nothing gained, so I dropped in a new crankshaft and bearings. The lifters and followers looked like sandpaper, but I left them in. Cylinder walls, pistons and rings appeared fine. A few more thousand miles and we sold the car to a friend (gave him all the gory details; he bought it anyway). He drove the car without incident for three or four more years before the rust finally led the way to the salvage yard. The engine didn't burn, leak, or otherwise oil before or after either repair occasion. FWIW, the oil-burning typically came about due to overheating from lack of coolant. Fairly early on, GM retroactively installed overflow systems and an additional temperature sensor to help avoid coolant-caused overheating issues. The linerless aluminum block was not otherwise that bad an idea; heck, it held up even in the absence of oil! For those who bad-mouth the linerless engine, it might be worth pointing out that millions of aluminum engines that don't use cylinder liners have been sold over the past several decades with very reasonable results.
None of this commentary negates the conventional wisdom that the Vega had real design issues and suffered from the typical GM 'cheapness'. I might note that later models were greatly improved in many ways. I'd be quite happy to drive a new '75 GT painted bright red with a black interior.