These are not straightforward comparisons with years and don't murder me on the figures if some are wrong. However it is the E34 and E39 generations that are the actual anomalies leading to the perception of the M5 vs M3 and then of course there is the fact that because of cost or simply availability fewer people even set foot in an M5... and so rely on the perceptions of articles with their own slants as well as those who chose the M3 supposedly over the M5 on merit and totally not because they'd have to buy an older one/couldn't stretch to a newer one... Also remembering that the M5 is a 4 door lounge on wheels that has much more practicality and "the tech" that everyone seems to like.
Don't get me wrong, the M3 is the benchmark... there is nothing quite like any of these cars which is why we love them. What I am talking about here is the perception that it is SO much heavier and somehow "like a boat"
(source: people who have never driven one). It is like a boat vs. a GT3 or something like my 4C/Lotus.
E28: 1465KG vs E30 1165 (195hp/ton vs 171hp/ton)
E34: 1710KG vs E36 1460 (182hp/ton vs 196hp/ton)
E39: 1795KG vs E46 1470 (220 hp/ton vs 230hp/ton)
Then something happens:
E60: 1848KG vs E90 1680 (250hp/ton vs 275hp/ton)
F10: 1870KG vs F80 1605 (299hp/ton vs 265 hp/ton)
F90: 1855KG vs G80 1810 (333hp/ton vs. 300hp/ton)
Another illustrative couple of references: my Alfa 4C with Novitec DP/Tune is at 341hp/ton which is another question I get frequently asked between my garagemates and how I am 'happy' with a tiny dumb little 1.75L when I have a beast next to it... A 992 GT3 RS has 362hp/ton and would (I think) be an appropriate upgrade.
Back on topic
I think perceptions of the M5 stem from E39 and earlier as well as people just not getting into them. From the E60 the power to weight differential has become much closer to the M3s and of course if you put a current gen M3 next to an E39, the effects of years of physical size gain will become very apparent.
That said, G90 is expected to be an eyewatering 2435kg so even with 718hp (295hp/ton), it is not going to be any faster than an F90 (333hp/ton) in a line and I am struggling to see how that would translate on a track. Watch how every influencer and media outlet is conveniently told to avoid comparisons to the F90 and focus on how it is as fast as a G80.
I think the perception of an M5 being 'too heavy' will once again be true. If I had R10 for every time someone at work/a client with an M3 or C63 went on about power to weight and didn't do the math, I'd have another M5 by now.
There is no bending of the laws of physics: It is usually that the reviewers or drivers don't expect power to have that much impact on weight (in exactly the same way when they get an extremely light car (orders of magnitude less weight) they cannot fathom how lightness changes dynamics). Unfortunately many have just experienced 'the average' and only have an idea of what lightness and 'big power' really are.
In our ratings of these cars, experience is often mentioned.... some will feel like a scalpel and some will feel like sledgehammers but in reality between generations we maintain a perception based on the badge even when they (by all measures and feeling) trade places or even take one another's places over time, certainly one gen vs the next.
