SMA MAKES EMER LNDG ON HWY AT NIGHT WHEN ENG QUITS DUE FUEL EXHAUSTION.

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THIS FLT WAS IN AN SMA THAT ENDED WITH A FORCED LNDG APPROX 30 MI E OF ALBUQUERQUE ON I-40. FUEL EXHAUSTION FORCED THE LNDG; BUT WITH LESS THAN 4 HRS OF FLT TIME ON LONG-RANGE TANKS; THIS UNUSUALLY HIGH RATE OF FUEL CONSUMPTION HAS NOT BEEN DETERMINED. THE FLT ORIGINATED ON FULL TANKS (88 GALLONS USABLE) AND SHOULD; THEREFORE; PERFORM TO NEARLY 5 HRS CRUISE WITH 45 MIN RESERVE. DURING THE FLT; ALL PRESSURES; TEMPS; AND FUEL FLOW INDICATIONS WERE NORMAL; HOWEVER THE FUEL GAUGES APPEAR TO BE STICKING AT CERTAIN LEVELS. BECAUSE OF THIS; I MONITORED FUEL CONSUMPTION BY SWITCHING TANKS EVERY HR AND LEANING THE MIXTURE TO 90 POUNDS PER HR FUEL FLOW. DURING A ROUTINE FLOW CHK; I NOTICED ABNORMALLY LOW FUEL QUANTITY IN BOTH TANKS. THIS WAS THE FIRST INDICATION THAT I MIGHT HAVE A PROBLEM; BUT AS MENTIONED EARLIER; THE GAUGES WERE NOT GIVING ME COMPLETELY ACCURATE INFO PREVIOUSLY IN THE FLT. WITH ALL OTHER SYS FUNCTIONING NORMALLY; I CONTINUED THE FLT. AT THIS POINT; I WAS INSIDE THE ANTON CHICO VOR ABOUT HALFWAY TO RUINS INTXN. I COULD SEE THE LIGHTS OF ALBUQUERQUE AND FELT THAT IT WAS THE NEAREST LIT ARPT IN MY VICINITY; SO I PULLED THE PWR AND MIXTURE TO A BEST ECONOMY SETTING AND CONTINUED. WITHIN MINS; THE R TANK RAN DRY AND THE ENG DIED. I SWITCHED TANKS ONLY TO FIND THE L TANK EMPTY ALSO. I RPTED THE PROBLEM TO CTR AND HEADED FOR THE NEAREST ARPT; MORIARTY; NM; AN UNLIT FIELD ABOUT 12 MI AHEAD. BECAUSE OF THE DARKNESS; I KEPT THE ACFT OVER THE INTERSTATE UNTIL I COULD HOPEFULLY SEE THE ARPT. IT BECAME APPARENT THAT I WAS NOT GOING TO MAKE MORIARTY; SO I LANDED THE PLANE ON THE HWY WITH NO INJURIES; RELATIVELY LITTLE DAMAGE; AND APPROX 25 GALLONS OF FUEL UNACCOUNTED FOR. OF COURSE; THE INVESTIGATION HAS NOT ENDED BUT SPECULATIONS FROM THE A&P AND THE FAA INSPECTOR INCLUDE: 1) THE FUEL SYS PRESSURIZED THE TANKS; PUMPING FUEL OVERBOARD. 2) FUEL TANK VENTS; FOUND TO BE STUCK WIDE OPEN; ALLOWED A SIPHON TO FORM; SUCKING FUEL OUT OF THE TANKS. 3) A COMPRESSION CHK FOUND THE #5 CYLINDER LOW AT 28 PSI. AS FAR AS WHAT I COULD HAVE DONE TO PREVENT THIS LNDG; I HONESTLY DON'T KNOW. I FOLLOWED THE BOOK. I RAN THE ENG AT 67%; AND ALL SYS CHKED. AT THE POINT WHERE I THOUGHT I MIGHT HAVE A PROBLEM; ALBUQUERQUE WAS MY NEAREST ARPT; AND I TRIED TO MAKE IT. AFTER THE OCCURRENCE; THE FAA INSPECTOR AND I DID SOME FIGURING AND FOUND THAT EVEN IF I HAD RUN THE PLANE FULL-RICH; I SHOULD NOT HAVE EXHAUSTED THE FUEL IN 3.9 HRS. I UNDERSTAND THAT THERE IS A PENDING AIRWORTHINESS DIRECTIVE ON THE FUEL SYS; AND THAT THIS IS NOT THE FIRST PROBLEM OF ITS KIND. IF THERE IS INFO ON THIS; I WOULD GREATLY APPRECIATE COPIES OR INFO ON HOW TO ACQUIRE IT.