NISSAN'S new turbo diesel is state-of-the-art because it incorporates just about all the technology known to the diesel world with direct injection, four-valves per-cylinder, twin overhead camshafts and twin balance shafts for smoothness. Clever timing of the injection pulses, plus high-speed swirl in the combustion chambers help compensate the tendency of direct injection to be noisier than a regular diesel. Another clever aid is the employment of a variable-vane turbocharger that alters blade pitch to regulate boost rather than a "wastegate" that bleeds off excess boost.