Faced with increasing U.S. emissions requirements and reduced compression ratios to deal with the upcoming lead-free gasoline, Triumph redesigned the Spitfire engine and increased the size to 1493 cc at the start of 1973. The diminutive roadster sold as the Triumph Spitfire 1500 from 1974 through the end of production.

The price rose to $2995 but the new motor bought 100 mph back in reach. Even with a 7.5:1 compression ratio it developed 57 bhp at 5000 rpm and Road & Track noted it was “a marked improvement over the past model,” recording 0-60 mph in 15.4 seconds and a top speed of 94 mph. “Of all the cars in the class, the Spitfire is probably the best,” it said.

The interior was redesigned with new seats and separate headrests, new instruments and walnut paneling on the dash. A smaller 3-spoke steering wheel improved knee room for the driver and inertia reel seatbelts were installed. A handsome steel hardtop was optional, but even bolt-on wire wheels were history. Radial tires were optional, as was overdrive on the all-synchro 4-speed.

Big rubber blocks came to the bumpers for 1974 along with a front spoiler. A new singe-rail transmission was added with better chosen gear ratios, intended to eliminate the need to change to close-ratio gears for competition. The Spitfire received its own version of the MGB “rubber bumper” in 1975 to handle 5-mph impact regulations. Though it was hefty, it was cleaner than the rubber bumpers stuck onto the MGB and Midget. Radial tires were now a no-cost option and California cars had catalytic converters.

Outside California, the 1976 Spitfire was still available with a 9:1 compression ratio which meant 71 bhp, up to 37 mpg, and considerably more performance. Further efforts were made by Triumph in 1977 with a new carburetor, redesigned cylinder head and intake and exhaust manifolds. The dashboard switches were changed to column stalks the same year and the seats were redesigned with houndstooth inserts. The steering wheel shrank still more, to 13.5 inches and the ignition switch moved to the steering column. The price was now $4500 and it would jump a further $600 in 1978, to $5150.

The last two years of production saw 5-inch wheels and a padded steering wheel, while the bumpers were moved away from the body and horsepower slipped again, to 52.5 bhp. By the time Triumph Spitfire production ended in August of 1980, 95,829 Spitfire 1500s had been built since 1973, with 62,471 of them sold in the U.S. The last Triumph Spitfire sold for an eye-watering $7365.