Used the E01 today so I asked a cop stationed at the entry point about this speed limit confusion. According to him, anything including 120 km/h and above will be dealt with. According to him they tolerate anything upto 119 km/h. It's an unwritten rule they're enforcing so that all the motorist on the E01 won't be caught speeding.
Also according to him, deducing the speed via the entry and exit times is total BS. Only what is caught on the radar guns apply.
Guys, please note that this is all according to this cop. Please do not adopt the 'shoot the messenger' policy if you guys are busted for doing 119 km/h or doing the trip in 35 mins