if you can't reflexively identify the year and make of that car by its taillights alone, stay out of my timeline
1959 was the glorious apotheosis of over-the-top Harley Earl / Virgil Exner googie car design, and it's been downhill ever since. Some of my favorites from that year: Cadillac Eldo, Chrysler Crown Imperial, Packard-Studebaker Hawk, Chevy Impala 
After '59 Harley Earl was pushed out at GM, beginning the era of Bill Mitchell's cool restraint. His signature designs: 63 split window Stingray, 65 Buick Riviera, '67 Cadillac Eldo, '67 Camaro
The car that really declared the 1950s were over was the Lincoln Continental. Compare the 1960 model with the 1961, designed by Elwood Engel
While Ford & GM were toning things down, Chrysler actually kept getting wackier for a few more years. Here's a 1962 Imperial with its crazy floating headlights & taillights. They toned down after Chrysler replaced Virgil Exner with Elwood Engel.
The car design that declared WW2 was over and that 1950's had begun was the 1949-51 "Shoebox" Ford. Compare the 1948 with the integrated fenders of 1949.
The '49 Ford was all new on the outside and in suspension, but still had the same basic flathead V8 design that was introduced in 1932. 1949 was also the debut of the Cadillac and Olds Rocket modern OHV V8, & all US car makers had their own by '55 (Ford in 1954)
Chrysler Corp had a dizzying array of Hemi motors in the 50's. There was a Chrysler, a DeSoto, a Dodge, and a Plymouth polyhead "semi hemi." Few of the parts exchange between them, and all are completely different from the 1960s Mopar 426 Hemi
Ford was notoriously reluctant to stray from tried & true tech. Believe it or not that 1948 car had the largely the same flathead V8-torque tube-I beam front axle-wisbone & buggy spring suspension as their 1932, and is even similar to the Model T's.
"Hemi" refers to the hemispherical or dome shape of the combustion chambers. Chrysler liberally swiped the design from Zora Arkus-Duntov's "Ardun" aftermarket OHV heads for the Ford flathead V8. He later became the Godfather of GM's racing program
During the same time Euro car makers were introducing overhead cam designs, most notably Jaguar, on smaller engines. The only American OHCs then were the 1967 Pontiac Tempest straight 6 and the mind-blowing Ford 427 SOHC
The first production US overhead cam engine was the tiny 1944 Crossley Cobra (COpper BRAzed). 44 cubic inches, 26 hp, powered the 'Hot Shot' clown-sports car. Crossleys were made in Cincinnati by a radio company.
correction, 1948
Where was I? Oh yeah, cars. The most durable of all 1950s engine designs was of course the Chevy Small Block V8, introduced in 1955 and available until 2003. They remain the object of love/hatred in the hot rod world.
Loved for their durability, availability of parts and speed equipment; hated for their ubiquity. Hot rodders refer to them as "Bellybutton" motors, because everybody has them.
Buick intro'd their first "Fireball" OHV 8 cylinder in 1931, but it was inline. It remained their main engine until the 1953 introduction of the famous "Nailhead" V8, so called due to its small valve diameters. It was available till 1966.
Buick later made a small all-aluminum 215 ci "Baby Nailhead," and Olds made a similar version. Incredibly light, and used in Indy cars. Also known as Rover V8s because they ended up in British Rovers & Land Rovers
A couple of underappreciated OHV V8s, the Studebaker and the Packard. Stude V8 came out in 1951 and owed a lot to Cadillac/Olds design. Packard was a laggard and didn't have it until 1955, too late to save the company; it was also used in AMC/Hudson/Nash cars.
In 1952-3 Studebaker sponsored an ill fated Indy program, using Stude V8 and DOHC heads made by Leo Goosen. Only a handful of the heads were ever made. When he was a teenager, my pal @BanksPower bought a spare pair from Goosen and made them into a hot rod motor.
Lest you question the performance potential of a Buick straight 8, behold Bombshell Betty. A modified Buick Fireball pushes this barn-on-wheels to 165 mph
