I've owned my 540i for about 6 years now. What a blast to drive - I actually prefer driving my 540i over my 911. The power is great, suspension very precise and brakes rock solid. The interior is awesome (great leather). This is my favorite 5 series body style. My 540i looks fast standing still. Gas mileage is about 18-19 combined. The problems cause me to selectively drive my 540i. The transmission is acting up again. I had the valve body rebuilt and everything was good. Then the transmission light came on and it goes in limp home mode. The radiator, fan, fan clutch, water pump have been replaced. Ditto for numerous seals and gaskets. Power steering fluid res. cracked.
Power band is wonderful. Rock solid feel at speed. Great steering feedback. Brakes are so strong. Performance far exceeds my expectations. Body is masculine, but it doesn't scream at you. Interior is great - lots of very nice, high quality materials were used. Corners very flat for a big car.
Transmission stinks! Too many maintenance issues. Leaks all over the place. Suspension maybe a little stiff for daily driving. Did I mention the horrible transmission problems!