I recently bought a secondhand 2009 Insignia 2.0 CDTI SE to replace my 2001 Toyota Avensis 1.8 VVTI. I hoped to improve fuel economy with my change in car. The Insignia, which is a diesel, has only just bettered this by returning 40.5mpg on my first tank (no motorway runs included yet). I decided to check the tyre pressure and consulted the manual to find the correct settings. I found there was the option of ‘comfort’ or ‘economy’ pressures and decided to try the economy settings. I have yet to empty a second tank to see if there is any measurable improvement (I expect it will only be slight) but I am concerned if the higher pressure could lead to accelerated tyre wear on the middle sections of the tyres. For the record the recommended pressures are: Tyres 225/55 R17: Front 32 psi (comfort), 39 psi (eco); Rear 29 psi (comfort), 38 psi (eco).