Looked them up on blackcircles and they're rated C for wet grip and E for fuel economy!?!?! A is good and G the worst. You will find a drop in fuel economy. That may or may not bother you, but an E rated tyre will make a noticeable difference. You can get other tyres for that size at a C rating, which will improve your economy. Sure they cost more, but then you have a £14,000+ car and tyres that last 30k miles. Surely that warrants an extra £100 over the 4 tyres for peace of mind of a higher quality tyre? On last thing. I had non low rolling resistance tyres fitted by mistake and my economy dropped by about 5 mpg. Doesn't sound a lot and you think you'd probably live with it. Just work out 5 mpg difference over 30,000 miles. Does it still save to go for the cheaper, less economical tyre? Your call.