I guess I'm probably due for a revisit to Disneyland. It has only been about 40 years since I was last there.
Besides, it looks like it's a kid's ride. Sometimes I feel that parents will say a ride "sucks" and the kid doesn't know how to feel about it. They see their parents didn't like the ride so they start not liking it imitating them. Sometimes adults need to understand how a child feels. As a rollercoaster fan, Gadget's Go Coaster is incredibly boring to me. But when you see a 5 year old's face light up on that thing? It's priceless.
SPIN WHEELS SPIN!
Also consider that a lot of the target audience of Cars is under the age of 10. I've never met an adult who is a fan of Cars but my cousins who are under 5 love it. And they're definitely not old/tall enough for Radiator Springs Racers.
Please tell me they are NOT testing at full speed!