Why this car matters
The 1968 AMC AMX 390 puts AMC's largest offered engine into its compact two-seat AMX. The 390 was optional, so the AMX name alone does not establish which engine a car received. AMC's Canadian brochure presents the 390 as a new engine and explains its forged-steel crankshaft and connecting rods. Factory engine description
Advertised engine output
The brochure's specification chart lists 315 hp at 4,600 rpm, 425 lb-ft at 3,200 rpm, four-barrel carburetion and 10.2:1 compression for the 390. These are factory engine ratings, not rear-wheel measurements. The chart does not explicitly identify a gross or net test standard, so its figures should retain that qualification in comparisons. This Canadian publication also needs to be distinguished from a U.S. order guide when checking market-specific equipment. Factory specification chart
What the period test actually records
Bill Sanders' March 1968 Motor Trend test lists 0–60 mph in 6.9 seconds and a standing quarter-mile in 15.2 seconds at 92 mph. Its specification box gives a 390, four-speed manual, 3.15:1 axle and E70×14 tires. However, the article describes testing both transmissions and says the automatic delivered the best times. The table does not resolve that attribution clearly enough to label these as a definitive four-speed result. Treat them as observations from this particular report, with transmission attribution uncertain. Motor Trend, pages 38–39
Engine, package and individual-car identity
Keep engine identity separate from Go Package equipment. A restored car's stripes, wheels or badges cannot establish its original engine, differential, brakes or option combination. Match the vehicle's records and hardware to the appropriate year and market before describing it as an original 390 Go Package car. The images on this page provide model and equipment context; they do not replace that individual-car evidence.
Production entries below distinguish the whole AMX line from the 390 subset and its transmission counts. Those totals are not a count of a particular paint, interior and option combination. Likewise, the base-price entry is separate from the dated auction observations; a no-sale bid is not a completed sale.