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 gather 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 Ferrari entry, however he would only be participating in a Formula 2 Ferrari 166. Sommer would be concentrating his efforts on the Formula 2 support race in which he would participate in the same car as the Formula 1 race. Peter Whitehead has 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 entries once again, as Louis Rosier and Eugène Martin are back to race alongside regular driver Yves-Giraud Cabantous. Subsequently, Rosier has loaned his privately owned Talbot-Lago T26C with which he has raced in Monaco to Harry Schell for the weekend. Philippe Étancelin has not been retained by the Talbot-Lago team, nonetheless he is still in attendance at Bremgarten in his own privately entered T26C. Johnny Claes makes up the final entry of the Talbot-Lago's in his privately owned car. Louis Chiron and Franco Rol are once again the Maserati entrants, however Rol would be forced to withdraw following the broken arm he sustained in the first lap at Monaco. Scuderia Achille Varzi has 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 were to compete in Switzerland.
The first driver selected is a unique choice, the reigning motorcycle 150cc World Champion and 500cc runner-up Nello Pagani, who 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 is 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 driver 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 motorsport 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 was 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 has been heavily modified, so much so it is renamed the 4CLT/50. The final entry sees another new manufacturer attempt to enter the Formula 1 ranks, Società Valdostana Automobili (SVA). The company, a subsidiary of the Fiat manufacturer, has built a Formula 1 car that in testing has proven highly unreliable albeit quick at times. Swiss driver Rudolf Fischer is due to drive the car, however its reliability problems force 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 only on the Formula 2 support race, their cars being better suited for the competition of the feeder series. The practice and qualifying times would take place on the Thursdays, Fridays and Saturdays of the racing weekend with the Grand Prix taking place on Sunday, June 4, 1950. On the first day of practice, Thursday, June 1, 1950, there is very little track activity, none of the Ferraris, Maseratis or the Talbot-Lagos are on 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 goes by, Alfa Romeo's test and reserve driver, Giovanni Guidotti takes a single Alfa Romeo out on an installation lap. The team plans to use only a single car on the first day of practice, when Guidotti returns to the pits after the initial checks, Giuseppe Farina takes over the car. After some time out on track, Farina hands the car over to Fagioli for a run. Fagioli's run is cut short when he encounters engine troubles forcing him back to the pits, Fangio therefore is forced to run in a second car for his stint. Fangio's run is thereafter untroubled and he is the fastest of the three Alfa drivers after the first day. On the second day of practice, Ferrari, Talbot-Lago and Maserati enter the fray and begin to set lap times. Over the course of the final two days of practice, Alfa Romeo remains in control of the leaderboard, however Ferrari has begun to make gains on their rivals. Of the three Alfas, Fangio has dominated throughout the three days, with Farina and Fagioli somewhat lagging behind. The Ferraris are clearly making improvements, Villoresi in the upgraded car is now only one second behind Fagioli. Alberto Ascari, racing in the standard 125 Ferrari is only 0.7 seconds off teammate Villoresi's best lap time. Étancelin, the former Talbot-Lago privateer who is frustratingly not retained by the team, is interestingly the fastest of the Talbot-Lago cars in practice. Giraud-Cabantous is one place behind him on the grid, being the fastest of the Talbot-Lago cars. Prince Bira is the fastest Maserati car in eighth followed by the two Talbot-Lagos of Martin and Rosier. Then come De Graffenried and Bonetto in their Maseratis, whilst the Formula 2 Ferrari of Sommer is in thirteenth place. Sommer has won the Formula 2 race on Friday, however his car cannot compete at the front alongside the lead cars. The final entries are made up primarily of the semi-professional private racers Claes, in fourteenth, and Pagani, in fifteenth. Chiron in his Maserati is disappointed to be only sixteenth after his sensational home race in Monaco. Whilst behind there are 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 would prove difficult as always; the track is notorious for its uneven surface, and the degrading tarmac would make the race around Bremgarten difficult, even in dry conditions. Fangio has a near perfect start, storming into the lead ahead of Farina and Fagioli. Behind them, Ascari overtakes Ferrari teammate Villoresi for fourth and then before the conclusion of the first lap he has moved past Fagioli as well. Giraud-Cabantous would not complete the first lap, his Talbot-Lago spears off at Eymatt corner; luckily, the Frenchman gets out of his destroyed car unscathed. At the conclusion of the first lap Fangio leads from Farina, Ascari, Fagioli, Villoresi, Bira, Étancelin, Rosier and Martin. Ascari is able to stick to the leading two Alfas whilst Fagioli appears to be dropping back into the secondary group. However, all hopes of Ascari challenging the Alfas are dashed when he goes into the pits to retire on lap four with a broken oil pump. Villoresi attempts to continue the Ferrari challenge, like Ascari he manages to pass Fagioli, however on lap nine he has to retire from 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 a suspension failure. Fagioli maintains third place, distanced to Fangio and Farina ahead of him, however has a strong gap to Bira's Maserati in fourth place behind him. On lap 15, Bira becomes the first of the front runners to come in for fuel. This leaves Étancelin in fourth position, however he immediately begins to encounter gearbox problems causing him to drop back behind the Talbot-Lagos of Rosier and Martin, leading to his eventual retirement on lap 25. The three Alfas 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, sees his fuel pressure system explode whilst coming in for his stop. Luckily neither he nor his mechanics are injured and after this mishap, his car is refuelled and he returns 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 outdrives himself and like Giraud-Cabantous before him, he goes off track at Eymatt corner.
Unluckily for him, the result has much more serious consequences, the car flips and Martin is thrown away from his car. Martin receives serious injuries in the crash and is urgently carried to hospital. With the Ferraris out of contention, the Alfas are unstoppable; by lap 33, Fangio, Farina and Fagioli all lapped the entire field. Fangio manages 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 regains his pace and catches up to Farina ahead of him. The three Alfas are running back to back to one another, that is until lap 33 when Fangio goes into the pits when he begins to detect engine troubles on his car. As the mechanics complete their inspection, it is evident that the problem is terminal and Fangio is forced to retire despite having dominated the weekend. Behind the Alfas, Bira is forced to come into the pits a second time due to mechanical troubles. He is able to continue, however he loses third place to Rosier's Talbot-Lago. Rosier's unique plan of going the whole race without stopping for fuel has paid dividends and gives him third position. The final few laps are uneventful, Farina leads, although Fagioli is ever in his tails, finishing only four tenths behind his teammate at the chequered flag. Rosier takes a comfortable third, a lap down on the Alfas. Bira comes home in fourth, a further lap down on Rosier. It is a frustrating result for the Thai Prince, he has driven well the whole race and had a chance for a podium if it was not for mechanical mishaps. He luckily is able to fend off Felice Bonetto who finishes fifth after his own early race mishaps. De Graffenried takes sixth place, the first driver of the non-points finishers. Motorcycle World Champion Nello Pagani had an uneventful race finishing in seventh, three laps down on the leaders. Chiron has a disappointing weekend and finishes ninth behind Harry Schell's Talbot-Lago. Claes is a further 4 laps down whilst Branca manages to finish in his old outdated 4CL, however he is seven laps down.
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 people, 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 cars to 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 metres 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 gap. Only Fangio’s mechanical accident on lap 31, which forced him to retire, has deprived 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 assumes 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. Giraud-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.