THE top gun at driving formula one cars very fast, Lewis Hamilton, has expressed concerns that new restrictions on testing will potentially reduce the reliability of this year's cars.

The new cars are technically untried in many areas beyond the controversial Kinetic Energy Recovery System.

There are new slick Bridgestone tyres with untried compounds, a mandated new aerodynamic package that could reduce downforce by as much as 50 per cent and all the usual pioneering technology seen before every new season.