It's all well and good raising the speed limit and to some extent I agree. The problem you have though, is although the cars are more capable at higher speeds and stopping quicker, you've still got the same idiots who can't drive properly as it is 
I've lost count the amount of times I've seen articulated lorries restricted to 56mph, having to overtake idiots on the motorway doing 50 
I personally think these prats shouldn't be allowed out, let alone on the motorway!!
Its wrong, however, to do what the last government tried, and to legislate to the lowest common demoninator.
TB's manifesto for motorways:
Speed limit 85/65 (dry/wet) for cars, 55 for HGV
Minimum speed limit 70/50 (dry/wet) for cars, (no min for HGV) with matrix signs if weather deemed too bad
On 3 lane motorways, only cars and car derived vans in outside lane. No trailers in outside lane.
No caravans or camper vans. Ever.
Anyone caught hogging middle lane to immediately have to take another test. 2nd offence, death.
For town traffic:
A minimum journey length of 2 miles. That means you can't take little thicko Johnny to school in the car, walk him you lazy fat ugly cow.
Reckon I stand a chance of election?