That engineless car routine was done once on the old "Candid Camera" TV program in the USA. They also did one with a VW beetle where they replaced its 10 gallon tank with a HUGE tank under the rear seat, and went a station and told the young guy to "fill it"...as I remember, he got 40-50 gallons in, and the VW was noticably settling over its rear axle before they stopped the joke.