C70(1) vs 850 wagon weight comparison

[eightfifty2x0]

Hi. So i wonder why the C70(1) is just around 20-30 kilos lighter than the 850 wagon? How can that be true? I read it on wikipedia that the C70(1) is "Coupé:[10]1,499–1,547 kg (3,305–3,411 lb)" and the 850 is "estate:1,465–1,570 kg (3,230–3,461 lb)" heavy-
I mean, how can a coupe be not much lighter than a wagon? Was the C70(1) made tougher?

[abscate]

The convertible had some frame stiffeners of substantial metal added underneath, at least

[eightfifty2x0]

Yeah, but the coupe is without all those mechanisms and the extra metal underneath. How can it still be so little less lighter? I expected it to be like 200-300 kilos less!