BONNEVILLE SALT FLATS — Of the 500-plus cars that showed up for the annual running of Speed Week, the one that drew the most attention on Thursday was small enough to easily fit into the pocket of a pair of jeans.

It was Hot Wheels' commemorative die-cast "Custom Otto" model. Thursday was the first stop on Hot Wheels' 40th anniversary tour and, in part, recognition of its 4 billionth car rolling off the production line.

When the Hot Wheels trailer opened, drivers, crew members and spectators formed long lines early Thursday, first to get a free commemorative Hot Wheels car and next to get the autograph of longtime designer Larry Wood.

The first Hot Wheels die-cast cars were produced in 1968. Since then, toymaker Mattel has sold more cars than all those produced by Detroit's Big Three automakers. The 4 billion cars involve the design of more than 800 models and 11,000 variations of those models. If the 4 billion Hot Wheels were placed end to end, the chain would wrap around the world more than four times.

"When we were trying to decide which vehicle would be our 40th anniversary model, we looked at the illustration that appeared on the first package," said Erin Sullivan, senior marketing manager for Mattel.

"We never turned that illustration into a real car. We decided to make that illustration into a real model. We're making several stops and at each stop we'll give away a model of a different color. We came to Bonneville first because this is the hotbed of auto racing."

On display was the ultimate Hot Wheel model, a 1:64-scale model cast in 18-karat white gold and accented with 2,700 diamonds with a total weight of 23 carats. The car has a price tag of $140,000. When the tour is over, the model will be auctioned off and proceeds will go to Big Brothers Big Sister of Greater Los Angeles and the Inland Empire.

After all the models were given away and all of the autographs signed, drivers and crews returned to the pits to get the full-size models ready to race for land-speed records.

Bonneville Speed Week runs through Saturday near Wendover.