An international breakthrough for the Aurelia B20 GT started with the series 3 (S3) edition. This series was brought on the market in 1953 and showed significant changes. The most important of these was a larger, more powerful engine.
The modified engine was enlarged to 2,451 cc and power output was raised to 118 hp @ 5000 rpm. Top speed of the S3 GT was now 185 kph, which put it in the performance car class, its rightful place. Its model name was changed accordingly to Aurelia B20 GT 2500. The engine received a new cylinder block, a single twin-choke Weber carburettor where previous Aurelia GTs had two single choke Webers, and a modified camshaft.
Most noticeable change to the exterior was of course the new rounded rear end. Other changes included a wrap-around rear bumper, a larger rear window and different headlight lenses. The dimensions of the GT were now 437 x 155 x 136 cm (length x width x height) and this remained the same until the end of the production of the Aurelia GT.
The S3 sold well but was short lived; after 720 of these had found a buyer it was replaced by the S4 GT in 1954. All S3 GTs still had right hand steering, which didn't help the export of this model. Even so the performance of the GT attracted international attention, assisted by impressive results by Lancias in international events like the Carrera Panamericana. As a result S3 GTs (and later series) are wider spread across Europe then previous series.

The Aurelia B20 S4 GT 2500 which was presented in 1954 righted a shortcoming of the S3 GT: the tendency to oversteer. Increase in performance had emphasized this weakness in the roadholding of the Aurelia and to correct this the original independent rear wheel suspension of the Aurelia was replaced with a De Dion type of suspension.
This improved roadholding and driving performance considerably. Added to this were new Vanderwell thin wall bearings and better oil filtration to enhance engine durability, a modified final drive ratio and larger brakes. The rest of the car remained largely unchanged, it practically had the same power to weight (1150 kg) ratio as the S3 which made it the most agile and popular of all Aurelia GTs.
Essentially the Aurelia GT was a 2-seater, though it had a multifunctional luggage board behind the front seats which could be converted to an uncomfortable seat for two short legged people and therefore was sold as a 2+2. The front bench seat could accommodate three people, helped by a steering column shift and the gearbox in the rear axle arrangement. Starting with the fourth series the Aurelia GT was also available with left hand drive (B20S), finally.
For those who wanted even more performance from their Aurelia GT there were tuning sets available. Most renown was the tuning upgrade offered by Nardi. It incorporated twin Weber carburettors, special camshafts and pistons and a limited slip differential. Additionally a modified exhaust system by Abarth and faster floor shift (like on this picture) could be fitted. Nardi enhanced Aurelia GTs often had an air scoop on the bonnet as a distinguishing feature. These tuned Aurelia GTs were considerably faster than the production model.

The visible differences between the third and fourth series Aurelia GT were limited. On the outside the most notable differences were new door handles, chrome plated push-button door handles replaced the cast metal swiveling door handles of previous series, and the addition of a reversing light in the rear. In the interior the instrument panel of the fourth series was updated near the end of its production run.
A fifth series Aurelia GT appeared in 1956, after 1000 GTs of the fourth series had been made and the berlina had been taken out of production. Where previous changes were aimed at improving the performance this new series was more biased towards comfort. The engine remained the same 2.5 litre unit as in the third and fourth series but revised cylinder heads and camshaft brought the power output down to 110 hp @ 5000 rpm. A new gearbox was fitted with hydraulic clutch instead of the mechanic one from before. Again the brakes were improved with larger and better cooled front drum brakes. Total weight of the car rose to 1210 kg. This all lead to a decrease in top speed to 176 kph as opposed to the 185 kph of the previous series.
Most important changes in the interior were a proper bench seat behind the front seats instead of a luggage board and an aluminum spoked steering wheel which replaced the unpopular plastic wheel. On the outside visible differences were minimal; only experts could see the difference by looking at the chromed trim around the windows, which was aluminum in previous series.

The revisions incorporated in the fifth series were meant to make the Aurelia GT a better all-round long distance touring car, but made the car less attractive to those who liked a sporty performance. It proved unpopular and after 299 had been made the fifth series was replaced by the sixth and last series of Aurelia GTs in 1957.
Lancia tried to improve performance while retaining the touring qualities of the previous Aurelia GT in this series. The compression ratio of the engine was raised and power increased to 112 hp @ 5000 rpm. In combination with revised gear ratios top speed was up to 180 kph, while vehicle weight was also higher at 1250 kg. This increase in bulk was caused by additions to make the car even more comfortable, like improved sound insulation and a smoother suspension by extra leaves in the rear springs.
Another comfort feature made the sixth series easy to recognize from the outside: opening quarter vents in the door windows. For the rest it looked similar to the previous series. Though less of a performance car than the fourth series the sixth series Aurelia GT was a fine car with good roadholding and lively steering combined with a high quality finish and comfort. Production of the Aurelia GT was stopped in 1958 after 621 cars of the sixth series were made.

The Lancia Aurelia GT was an expensive car in its time. It competed with cars like the Aston Martin DB 2 (also introduced in 1950 and with similar looks), Jaguar XK 120 and of course the Alfa Romeo 1900 C Sprint. At a total production of 3871 cars it was quite successful in that class.
Nowadays a Lancia Aurelia GT is a coveted classic which is equally suited to everyday driving as to taking part in classic car rallies or in concourses. Many still fall in love with its good looks and its qualities and as a result an Aurelia GT is quite valuable. Most popular are the 2,5 litre versions and especially the fourth series. The first two series are hard to find outside Italy and left hand drive cars come at a premium because the are relatively rare (except for the sixth series, of which the majority is left hand drive). Fortunately many Aurelia GTs have survived and also the availability of parts is good, though they are expensive.