Before what? It was a typical biggest prize in game shows in the 70’s (unless they were giving away a boat or something). Some of the earlier shows it might be an appliance made by the show’s sponsor.

@Zaku Before the automobile was the top prize.

Oh my god…

Washers dryers, appliances,trips etc

Going back over a century, a car is the single most expensive thing a person can buy, other than a house. So that’s why it has always been the biggest possible prize for game shows. There was no “before”; before that there was no radio or television.

Some basic facts seem to be missing from the perspective of this questions such as:

* There are multiple game shows, which offer different reward structures. These vary from “a million dollars” or more, to cars and boats, to vacations, lots of various in-kind prizes, dates with strangers, education, jobs, promotion of a product the contestant designs, or just a title or prize with no value at all.

* A car is not currently THE best prize in a game show (is it even in any current show?). There were shows at least 40 years ago where people could win a large boat, multiple cars (which started getting ridiculous on some shows “IT’S A BRAND NEW CAR!” – um yeah it’s another Buick Skylark, great, I have seven now), or much more money than several cars were worth, etc.

So really the answer is “never, except maybe on some one show where the best prize was a car”?

@Zaku O.k. from Let’s make a Deal remake? After Monty Hall. Thanks for improving my question. I would think cash and maybe a Recreational vehicle (R.V.) would also be a top prize.

Deal or no Deal I think had the highest cash prize of 2.5 million dollars.

The wall might be more. What is the highest cash prize for any game show?

1999:
The $1,000,000 Chance of a Lifetime
Who Wants to Be a Millionaire

2000:
Perfect 21 (someone won $1,120,000)
Greed (someone won $1,410,000, another person $1,765,000)

2001:
Millionaire (someone won $$2,180,000)

2004:
Who Wants to Be a Super Millionaire ($10,000,000 top prize, but no one beats 1 million)
Jeopardy! (Jennings won $2,197,000, then Ultimate Tournament of Champions winners at $3,270,102 and $3,022,700)

2005:
Jeopardy! (top winners now at $3,570,102 and $3,923,414.29)

See https://en.wikipedia.org/wiki/American_game_show_winnings_records