Lyon looks like there was well over ten kilometers of full throttle. Made me wondering what was track with all time longest full throttle section and do we have map of it?
I was reading only the other evening in Volume 2 of Pomeroy's The Grand Prix Car that the circuit for the first GP de l'ACF in 1906 featured a section of near-straight road for nearly 20 continuous miles, which, at 90-100 mph, would have probably taken nearly 15 minutes from end to end.
Further to you point regarding the Lyon circuit, I'm not sure what the return road from the far end of the circuit, through Le Pont Rompu (Broken Bridge) was like then, but, on Streetview it now seems pretty straight. Certainly the outward leg from Givors was (and to a fair degree still is) narrow and not very straight as it was a corniche road cut into the hillside of the Gier valley.
The following link is in French, but it's fairly easy to understand the place names and it contains several period photos:
Edited by cpbell, 21 June 2017 - 14:26.