The planes on the Silver City Airways were Bristol 170 Superfreighter. I remember flying different routes on them with my Renault 4 or my wife's Sprite Mk. II. The twelve seats cabin was not presurised and very drafty. Blankets were distributed to the passengers.
The routes I used were Cherbourg - Southampton, Le Touqued Lydd and Calais - Shouthend on Sea. This last route was very convenient as at the time I used to go to Cambridge and the M 2 was not build so this avoided the driving in Kent were the roads have hardly improved since.
More about Silver City Airways here :
www.silvercityairways.com/the_company.htm
Dieppe July 1956.
The price was not more expansive than by ship but much faster. It must be remembered that in the late 50's the cars were lifted into the hull of the ship by a crane as shown above. My fathers car been loaded in Dieppe.
Dinky Toys 24u Simca Aronde Elysée.