The mementos in question are fake tiger tails from the early 60s, when motorists all over the world were tying them to the caps of their petrol tanks and sporting bumper stickers that declared: "I've got a tiger in my tank."
The fact that some 2.5 million tails were sold in the US alone - and that they're still in demand - is testimony to the durability of the campaign that convinced drivers that Esso fuel was so powerful that it was the equivalent of having a huge beast in their petrol tanks.
"Put a tiger in your tank" was a slogan created in 1959 by Emery Smith, a young Chicago copywriter who had been briefed to produce a newspaper ad to boost sales of Esso Extra.
The tiger wasn't Smith's invention. He'd first appeared as a mascot for Esso in Norway around the turn of the 20th century. But it wasn't until the end of the Second World War - and the resumption of petrol advertising - that the tiger made his US debut.
He was a very different character back then. Cute, amiable and in cartoon form, he closely resembled Tigger in Winnie-the-Pooh and was intended to represent a new post-war optimism after years of shortages. He also gave an identifiable face to Esso in a market where brand differentiation has never been easy.
It was in 1964 that the character really hit his stride with a campaign developed by McCann Erickson. As Esso sales soared and the advertising be-came the talk of adland, Time magazine declared 1964 to be "The Year of the Tiger" along Madison Avenue.
The oil crisis of the early 70s put a stop to any conspicuous petrol consumption and, with little advertising activity taking place, Esso switched its efforts to promoting its pioneering role in North Sea oil exploration.
The task of reflecting this change of emphasis in advertising terms fell to the long-serving McCann senior creative Chester Posey. He chose to represent the new global reality for the newly named Exxon Mobil by swapping the cartoon tiger for a real one and the line: "We're changing our name, but not our stripes."