Having just seen a Lancia D50 in the " flesh" again it is remarkable compact car and , famously proved as fast as the MB W196 in the early 1955 races.
Reading an article in Vintage motorsport ( Jan/Feb 2022 issue ) it quotes the weight of the D50 as 1367lb vs 1841lb for the W196. That is a 25% weight advantage vs the Mercedes for only 260 bhp vs 290 bhp power disadvantage.
So the D50 should have out-accelerated the W196.
The 1841lb for the W196 is repeated on many google sources and I would sort of expect the W196 to weight more due to its MB tool room construction and complex engine plus inboard front brakes etc.
The D50 weight is still well above the 1068lb quoted by Tony Rudd for the BRM P27.so , whilst light, it was not the lightest 2.5 litre car by any means
Was the W196 really that much heavier than the other 2.5 litre cars?