The third round of the championship is held at the Indianapolis Motor Speedway, however none of the World Championship competitors seriously considered it as a grand prix event and would choose not to participate. The regular drivers regroupe for the fourth round of the world championship at the Swiss circuit of Bremgarten. Alfa Romeo drivers Giuseppe Farina and Juan Manuel Fangio are tied on 9 points apiece. Shortly behind in the championship is the third Alfa Romeo of Luigi Fagioli and Alberto Ascari's Ferrari, both drivers on six points. Ascari have won the event the previous year for Ferrari, however with the return of the dominant Alfa's for 1950's, the trio of Farina, Fangio and Fagioli are expected once again to be the favourites. Alberto Ascari and Luigi Villoresi are expected to be the Alfa's main rivals once again with their competitive 125 Ferrari's. Villoresi would be participating with a chassis with an updated rear suspension, twin overhead camshaft engine and 4-speed gearbox in Ferrari's latest effort to reduce the performance deficit to Alfa Romeo. Raymond Sommer is the third works Ferrari entry, however he would only be participating in a Formula 2 Ferrari 166. Sommer would be concentrating his efforts on the Formula Two support race in which he would participate in the same car as the Formula 1 race. Peter Whitehead have also entered his private 125 Ferrari, however after his serious mechanical problems in Monaco, he is forced to withdraw for the second race in succession. Talbot-Lago have increased their works entry once again, Louis Rosier and Eugène Martin returned as works entries to race alongside regular driver Yves-Giraud Cabantous. Subsequently, Rosier have loaned his privately owned Talbot-Lago T26C that he have raced in Monaco to Harry Schell for the weekend. Philippe Étancelin have not been retained by the works Talbot-Lago outifit, nonetheless he was still in attendance at Bremgarten in his own privately entered T26C.
Johnny Claes make up the final entry of the Talbot-Lago's in his privately owned car. Louis Chiron and Franco Rol are once again the works Maserati entrants, however Rol would be force to withdraw following the broken arm he sustained in the first lap pile-up at Monaco. Scuderia Achille Varzi have seen both of their drivers José Froilán González and Alfredo Piàn injure following the aftermath of the Monaco race, the team was therefore forced to look for a new driver if they are to compete in Switzerland. The first driver selected is a unique choice, the reigning motorcycle 150cc World Champion and 500cc runner-up, Nello Pagani is chosen as their entry for the Swiss round of the championship. The motorcycle World Champion is the winner of the Swiss Motorcycle Grand Prix the previous year and aside from his skill in bikes was also an adept car racer, having been a double winner of the Pau Grand Prix. The team's second driver is a relatively unknown local driver called Antonio Branca. Branca is an inexperienced pilot who primarily entered only local Swiss events, the question of how he managed to raise the finances to race in the event has always been somewhat of a mystery. He is rumoured to be financed by a rich lover that gave him the freedom to enter the prestigious motor racing events. Enrico Platé was with his standard entry of Emmanuel de Graffenried and Prince Bira. Reg Parnell is due to enter, returning to his Scuderia Ambrosiana team, however his entry was withdrawn prior to the event. The last Maserati entry is that of Felice Bonetto of Scuderia Milano. Both team and driver would make their debut in Bremgarten, the Milano-entered Maserati 4CLT/48 entered by the team have been heavily modified, so much so it was renamed the 4CLT/50. The final entry saw another new manufacturer attempt to enter the Formula 1 ranks, Societa Valdostana Automobil (SVA).
The company, a subsidary of the Fiat manufacturer had a built a Formula 1 car that in testing have proven highly unreliable albeit quick at times. Swiss driver, Rudolf Fischer, is due to drive the car, however its reliability problems forced the team to withdraw from the event. Simca-Gordini are a notable absence from the grid, the team would be in attendance over the Grand Prix weekend, however they preferred to focus on only the Formula 2 support race, their cars being better suited for the competition of the feeder formulae. The practice and qualifying times would take place over the Thursday, Friday and Saturdays days of the racing weekend with the Grand Prix taking place on the Sunday June 4, 1950. The first day of practice on Thursday June 1, 1950, is very little track activity, none of the Ferrari's, Maserati's or the works Talbot-Lago's are presence on the track. However Louis Rosier is practicing in his privately owned Talbot-Lago, before he would hand the car over to Harry Schell and return to his works entry for Friday. The only team to get serious track time on Thursday is that of Alfa Romeo. As the session give underway, Alfa Romeo's test and reserve driver, Giovanni Guidotti took a single Alfa Romeo out on an installation lap. The team planned to use only a single car on the first day of practice, when Guidotti returned to the pits after the initial checks, Giuseppe Farina took over the car. After some time out on track, Farina hand the car over to Fagioli for a run. Fagioli's run is cut short when he encountered engine troubles forcing him back to the pits, Fangio therefore is force to run in a second car for his stint. Fangio's run is thereafter untroubled and he is running the fastest of the three Alfa drivers after the first day. On the second day of practice, the Ferrari's, Talbot-Lago's and Maserati's enter the fray and began to set lap times. Over the course of the final two days of practice, the Alfa Romeo's remain in control of the leaderboard, however Ferrari have begin to make gains on their archrivals.
Of the three Alfa's, Fangio have dominate throughout the three days, with Farina and Fagioli somewhat lagging behind. The Ferrari's are clearly making improvements, Villoresi in the updated car is now only one second behind Fagioli in the updated Ferrari car. Alberto Ascari, racing only in the standard 125 Ferrari is only 0.7 seconds off teammate Villoresi's best time. Étancelin, the old Talbot-Lago privateer who is frustratingly not retain by the works outfit, however he interestingly is the fastest of the Talbot-Lago cars in practice. Giraud-Cabantous site one place behind him on the grid, fastest of the works Talbot-Lago cars. Prince Bira is the fastest Maserati car in eighth followed by the two Talbot-Lago's of Martin and Rosier. Then came De Graffenried and Bonetto in their Maserati's, whilst the Formula 2 Ferrari of Sommer is in thirteenth. Sommer his won the Formula 2 race on the Friday, however his car is lacking the drive to compete at the front alongside the lead cars. The final entries are make up primarily of the semi-professional private racers, Claes is fourteenth whilst Pagani was fifteeenth. Chiron in the works Maserati is disappointed to be only sixteenth after his sensational home run in Monaco. Whilst behind have come Branca and Schell, the young rich private entries rounding out the bottom of the field. The weather in Bremgarten is warm and sunny; ideal racing conditions. The circuit as ever would prove difficult; the track is notorious for its uneven surface, and the degrading tarmac would make a race around Bremgarten difficult, even in dry conditions. Fangio make a near perfect start, storming into the lead ahead of Farina and Fagioli. Behind them, Ascari past Ferrari teammate Villoresi for fourth and then before the conclusion of the first lap he have move past Fagioli as well. Giraud-Cabantous would not complete the first lap, his Talbot-Lago speared off at Eymatt corner, luckily the Frenchman exit his destroyed car unscathed.
At the conclusion of the first lap Fangio led from Farina, Ascari, Fagioli, Villoresi, Bira, Étancelin, Rosier and Martin. Ascari is able to stick to the leading two Alfa's whilst Fagioli appear to be dropping back into the secondary pack, however hopes of Ascari challenging the Alfa's are dashed when he pull into the pits to retire on lap four with a broken oil pump. Villoresi attempt to continue the Ferrari challenge, like Ascari he manage to pass Fagioli, however on lap nine he had to pull out of the race with a blown engine. The final Ferrari left of Raymond Sommer is stuck in the midfield with his uncompetitive Formula 2 166. Sommer would then later go on to retire with suspension failure. Fagioli maintain third, distanced to Fangio and Farina ahead of him, however held a strong gap to Bira's Maserati in fourth place behind him. On lap 15, Bira become the first of the front runners to come in for fuel. This left Étancelin in fourth position, however he immediately begin to encounter gearbox problems causing him to drop back behind the works Talbot-Lago's of Rosier and Martin, leading to his eventual retirement on lap 25. The three Alfa's have already opened up a tremendous lead, their fuel stops went without trouble, the trio easily getting out ahead of Bira's Maserati. In a more dramatic stop, Bonetto's Maserati who is competing in the midfield, say his fuel pressure system explode whilst coming in for his stop. Luckily neither him or his mechanics are injured and after this mishap, his car is refuel and return to the race. The closest battle on the circuit is for fourth and fifth place, Louis Rosier is being challenged hard by teammate, Eugene Martin. On lap 19, Martin outdrove himself and like Giraud-Cabantous before him, he went off at Eymatt corner.
Unluckily for him, the result have much more serious consequences, the car flip and Martin is thrown from his car. Martin receive serious injuries in the crash and is urgently rush to hospital. With the Ferrari's out of competition, the Alfa's are undominatable, by lap 33, Fangio, Farina and Fagioli all lapped the entire field. Fangio manage the lead out front whilst behind him Farina is pushing hard to close the gap, Farina earlier set the fastest lap of the race but still he could not unseat Fangio. After his poor start to the race, Fagioli regain his pace and caught up to Farina ahead of him. The three Alfa's are running back to back to one another, that is until lap 33 when Fangio pull into the pits when he begin to detect engine troubles on his car. As the mechanics completed their inspection, it is evident the problem is terminal and Fangio is forced to retire despite having dominated the weekend. Behind the Alfa's, Bira is forced to come into the pits for a second time due to mechanical troubles. He is able to continue, however he lost third to Rosier's Talbot-Lago. Rosier's unique plan of going the whole race without stopping for fuel have paid dividends and land him third position. The final few laps are uneventful, Farina led, although Fagioli is ever in his tails, finishing only four tenths behind his teammate at the chequered flag. Rosier take a comfortable third, a lap down on the Alfa's. Bira come home in fourth, a further lap down on Rosier. It is a frustrating result for the Thai Prince, he have driven well the whole race and have a chance for a podium if not for mechanical mishaps. He luckily is able to fend off Felice Bonetto who finished fifth place after his own early race mishaps. De Graffenried take sixth place, the first driver of the non-points finishers. Motorcycle World Champion, Nello Pagani, have an uneventful race, finishing the race in seventh, three laps down on the leaders. Chiron have a disappointing weekend to only finish ninth behind Harry Schell's Talbot-Lago. Claes is a further 4 laps adrift whilst Branca managed to finish in his old outdated 4CL, however he is seven laps adrift.
The fast and tricky Bremgarten Forest circuit-the scene of the 10th Swiss Automotive Grand Prix-saw a dazzling new affirmation of Italian industry. Held in front of an enthusiastic crowd of about 60.000, the fourth round of the world championship consecrated the clear superiority of the Alfa Romeo 158s. The race, made difficult by the intense heat that put men and machines to the test, was full of twists and turns. At the start Ascari took second behind Fangio; Farina secured third place, while the elderly but ever-valiant Fagioli slotted in between Villoresi and Prince Bira in a Maserati. The six cars passed by the grandstands on the second lap within a few meters of each other, but by lap three. Ascari was forced to stop in the pits a first time and on the fifth he retired. Meanwhile Farina boldly passed Fangio and set a new track record for the category, lapping in 2'41"6 at a speed of 162.178 km/h. On the tenth lap another twist: after Farina and Fangio, always fighting for first place, Fagioli passed under the grandstands alone. Almost at the same time the loudspeaker announced the retirement of Villoresi, who up to this point had been fighting validly for third place. The crowd greeted the news with regret. Practically the race was over at this point. The Alfa Romeos, with the three Fs, Farina, Fangio, Fagioli, in the lead, gradually improved their lead. Only a mechanical accident touched Fangio on lap 31, which forced him to retire, proved the Milanese manufacturer of a well-deserved three-fold victory. For the lead Farina and Fagioli contested a genuine final sprint, and the Turinese won by a narrow margin. With the victory in Berne, Giuseppe Farina decisively assumed the lead in the standings for the title of World Motor Racing Champion, clearly distancing Fangio, Ascari and the American champions. A few accidents, fortunately not serious, befell the Talbot racers. Glraud-Cabantous went off the track on lap nine but was miraculously unharmed, while his compatriot Eugenio Martin, whose car overturned in a difficult downhill corner, was transported to the hospital with a fractured femur.