One driver was clocked travelling at 241 km/h (about 150 mph) on the RD 177 between Rennes and the small town of Redon – more than double the 110 km/h (68 mph) limit.
The other was speeding at 193 km/h (120 mph).
It is understood that both drivers, who are aged about 40, were travelling back to St Malo when they were caught in a speed check.
One of the motorists was alone and the other was travelling with his son.
The two men were fined 2,000 euros and had their driving licences confiscated until they appear in court in Redon in the coming weeks.
And their cars – a Porsche 997 Turbo, which sells for about £100,000 and has a top speed of 194 mph, and Porsche 911 Carrera, which starts at £73,500 and can reach 179 mph – were seized pending the court case.
However, even if the French magistrate bans the two men from the road during the forthcoming court case, the ban would not apply in Jersey.
Bans imposed in other jurisdictions, including the UK, also do not apply in the Island.
Acting Inspector Paul Smith, of the States police, urged Islanders travelling abroad to ensure that they abide by the speed limits.
‘We would always hope that any Islanders travelling outside Jersey respect the traffic legislation of whatever country they are in.
The dangers do not change just because you may be on holiday. Inappropriate speed is a danger to both yourself and others.
‘The difference of a few miles an hour can mean the difference between life and death.
‘The faster someone is driving, the less time they have to stop if something unexpected happens.
‘On top of that, it is quite likely that you will be unfamiliar with the roads.
‘The speed limits are there for a reason – for your protection and for the protection of other road users.
‘Being stopped for speeding abroad may result in the loss of your ability to continue with your holiday, the fines can be expensive, and there may be the knock-on effect for your own motor insurance premium.’
