Narrative:

Prior to the trip; I fueled the airplane and assured myself that it was fully 'topped off'. (Its fuel capacity is 115 gallons in the mains and 20 additional gallons in the baggage holdout tank--5.5 hours of endurance; plus IFR reserve). Enroute; the CFI and I closely monitored fuel burn per the manufacturers specs. We figured it to have been 77 gallons.prior to departing [for the next leg]; (a thirty minute hop; at most); I did some pattern work (2 'touch and gos' and one full stop). By our calculations and the fuel gauges; we believed that we had 30 gallons remaining (without regard for the aux tank). Conditions for the short hop were ideal - no wind; clear skies.I elected to do a straight in approach. At approximately 3 miles out; however; with gear and flaps extended; the engine quit. A restart was unsuccessful. On short final; I could see that I wouldn't make the airport; and to avoid some very hostile terrain short of the runway; I made a decision to sidestep and land on the interstate.the landing; thankfully; was uneventful; with no injury to anyone or damage to property; including the airplane. It was towed from the interstate by tug up to the airport and hangared for the night.in the confusion and stress of the situation; and 'newness' of the airplane; I did not think of attempting to transfer fuel from the aux tank (the mains as it turned out were 'dry'). In hind sight; of course; on my first cross country in an unfamiliar aircraft. I should not have relied on my calculations and the fuel gauges. I should also have become thoroughly familiar with the auxiliary fuel transfer system.

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Original NASA ASRS Text

Title: C210R pilot reported landing on a highway after experiencing fuel exhaustion in flight.

Narrative: Prior to the trip; I fueled the airplane and assured myself that it was fully 'topped off'. (Its fuel capacity is 115 gallons in the mains and 20 additional gallons in the baggage holdout tank--5.5 hours of endurance; plus IFR reserve). Enroute; the CFI and I closely monitored fuel burn per the manufacturers specs. We figured it to have been 77 gallons.Prior to departing [for the next leg]; (a thirty minute hop; at most); I did some pattern work (2 'touch and gos' and one full stop). By our calculations and the fuel gauges; we believed that we had 30 gallons remaining (without regard for the aux tank). Conditions for the short hop were ideal - no wind; clear skies.I elected to do a straight in approach. At approximately 3 miles out; however; with gear and flaps extended; the engine quit. A restart was unsuccessful. On short final; I could see that I wouldn't make the airport; and to avoid some very hostile terrain short of the runway; I made a decision to sidestep and land on the interstate.The landing; thankfully; was uneventful; with no injury to anyone or damage to property; including the airplane. It was towed from the interstate by tug up to the airport and hangared for the night.In the confusion and stress of the situation; and 'newness' of the airplane; I did not think of attempting to transfer fuel from the aux tank (the mains as it turned out were 'dry'). In hind sight; of course; on my first cross country in an unfamiliar aircraft. I should not have relied on my calculations and the fuel gauges. I should also have become thoroughly familiar with the auxiliary fuel transfer system.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.