I do aircraft component welding. I also do certified brazing on structural components. Gas welding, Tig, stick and brazing along with many other forms of welding can be strong enough when the joint is engineered properly. Your car is likely spot welded!

On vintage Brittish race cars brazing was used to attach the suspension to the tubes. It was done in a unique way that still has merrit today. The tubes were tacked with braze in a "T" coming off the frame. Then brass was used to make the entire assy large enough to become a solid post rather than a "T".

The reason was that the low heat used while brazing did not affect the temper of the frame. When those cars crashed, they bent up like a pretzel, but never ever cracked or broke. Quite unlike American race cars of the time. The advantage was significant and allowed cars like the Lotus to weigh much less and outperform the competition.

Personally, I like tig the best.

Chris