l have purchased a BMW 318IS 1995 and it is incredibly uneconomical and sluggish for a 1.8Litre. l dont mind the sluggish part but l would atleast expect it to be fuel economical but seems to really go through fuel quite badly! What could this be caused by? It has been regularly service. l have got wider tyres than normal, 215mm. Could this be the cause of this problem?

Not if they re the right size. l suspect something s up with the engine is computer. Take it to a reputable BM mechanic and let him check the entire engine and fuel line. It could also be a leak but that does not cause the sluggishness. It really sounds like the car is badly in need of some good thorough service.

its a old car, engine loses power overtime. you might need to check the compression in each cylinder of the engine and make sure they each are making enough power. tires arent the problem.

YES, tire width can affect ur fuel economy. Wider tires make for higher rolling resistance, so it takes more fuel economy to keep ur car moving. l would recommend installing narrower, high-rolling resistance tires. You should also inflate ur tires to the maximum inflation listed on the sidewall to minimize rolling resistance.

Take a look at ecomodder.com for more info on the effects of wide tires on ur fuel economy.

By the way, nice car. l had a 318ti a few years ago, & l managed 34 MPG (US).