The 535d has all the luxury trappings of a BMW 5-series, and the diesel doesn't interfere with the comfort. If you listen real hard you can detect diesel ping occasionally but the outside exhaust note doesn't give away much. With 391lb-ft of torque available at just 1,500 rpm, a silky-smooth 6-speed automatic transmission and a 50/50 weight balance, getting away from the stoplight is an impressive exhibition. BMW says 0-100 km/h or 62 mph takes just 6.5 seconds. Mashing the throttle for quick bursts was the limit of my test opportunity but that was enough to convince me that there is no loss of performance with this diesel.

The 3-liter inline six engine features a variable twin-turbo system designed to eliminate turbo lag at low rpm and provide added boost at higher rpm. The smaller of the two turbos is mounted very close to the cylinder head so it can spool up quicker. The larger turbo is mounted out of the way. Based on engine speed, a series of valves diverts the airflow from one or both of the turbos. Both turbos will spin at low rpm but only the small turbo actually works hard enough to provide boost. As the engine speed picks up, the larger turbo gets more exhaust flow, therefore it spins faster and can start compressing air that is then directed to the small turbo for additional compression. Finally, as the engine really gets up to speed and large turbo is working at maximum boost, the smaller turbo is cut out of the system. Another valve regulates the total boost. The engine is rated at 272 horsepower at 4,400 rpm with peak torque of 413 lb-ft at 2,000 rpm.

Now that many wealthy consumers drive 1-ton diesel pickups to tow their RVs and horse trailers, there shouldn't be so much of a stigma attached to diesels in the luxury market. I'm quite sure if anyone has a doubt as to the performance and comfort of a diesel car, the 535d will cure them of any apprehension. If this vehicle was already available, the gas savings would be tremendous to consumers. Bring it here, fast.