The fine also leaves many of his fellow drivers wondering what they can say about their new cars without incurring NASCAR's wrath.
Hamlin couldn't understand why he was at the center of NASCAR's latest tempest over its drivers' media comments. He compared the new race car unfavorably to last year's car, along with lamenting the overall quality of racing last week in Phoenix.
Although Hamlin's brief comments were barely noticed last weekend, NASCAR -- clearly concerned about the Gen-6 car's public perception -- leveled a significant fine against him before Thursday's open test of the new car at Las Vegas Motor Speedway.
"Ultimately, I'm not OK with it," Hamlin said outside his hauler after the morning test. "This is the most upset and angry I've been in a really, really long time about anything that relates to NASCAR."
Hamlin actually ran well last Sunday in the second race for NASCAR's new Gen-6 race car in Phoenix, finishing third in a fairly dull race that featured no passes for the lead in the final 189 laps of Carl Edwards' victory.
But when Hamlin was asked on pit road how he liked the car, he said: "I don't want to be the pessimist, but it did not race as good as our generation five cars. This is more like what the generation five was at the beginning."
NASCAR deemed Hamlin's remarks as detrimental to stock car racing, saying that while drivers get "ample leeway in voicing their opinions when it comes to a wide range of aspects about the sport, the sanctioning body will not tolerate publicly made comments by its drivers that denigrate the racing product."
That didn't help Hamlin's bewilderment at his fine in a sport known for frank talk about every aspect of competition.
"It's an opinion. It's not even a bad one," Hamlin said Thursday. "I don't want to make things worse than they already are, and this is something that was absolutely nothing that got blown into something, and it's just going to be worse for them, so just let them deal with it.
"The truth is what the truth is, and I don't believe in this," Hamlin added. "I'm never going to believe in it. And so as far as I'm concerned, I'm not going to pay the fine. If they suspend me, they suspend me at this point."
Hamlin might not have a choice: According to NASCAR rules, unpaid fines may be deducted from a driver's purse or point fund earnings.
NASCAR vice president of competition Robin Pemberton said Hamlin is allowed to appeal his fine, and NASCAR apparently isn't in a rush to collect it. Section 12 of the NASCAR rule book states fines must be paid "promptly," but gives no specific timeframe, and says unpaid fines "may result in suspension."
Pemberton indicated nothing would happen this weekend or any time soon.
"We give them quite a bit of latitude, but you can't slam the racing," Pemberton said. "You can't slam your product. That's where it crosses a line."
NASCAR's decision on Hamlin's remarks surprised many drivers, leaving them uncertain what they could say. When Clint Bowyer was asked how Thursday's test went in his Toyota Camry, he put on a humorously blank expression and replied: "It's good. The car is good. Everything is very, very good."
Jeff Burton also wasn't sure how to react.
"I feel like it's a little bit of an overreaction on NASCAR's part," Burton said. "I do understand there's been a tremendous amount of effort that's gone into building this car ... and making racing more exciting to watch. In my eyes, this is the most work that's ever been done to create a car for the fans. I'm sure that has something to do with the decision for the penalty. NASCAR has got to be careful not to be too strict on the drivers. I want to be able to be who we are."
The Gen-6 car was developed by NASCAR last year with heavy input from the manufacturers to improve the on-track product. Drivers have been asked to be careful in how they publicly discuss the car, and NASCAR has put together a tremendous marketing effort in an attempt to avoid the poor reception the previous model received.
Fans never warmed up to the "Car of Tomorrow" in part because drivers panned it from the very beginning. Kyle Busch won the debut race in the "Car of Tomorrow" and blasted it in Victory Lane, and the car never stood a chance after that.
"We're so early into it," Pemberton said. "You're making a mistake if you comment on the worst or the greatest racing ever. The first part of the season, we run on so many different racetracks, and we're so busy. ... Positive or negative, you cannot read too much into any of this stuff. This is a long-term deal here, years and years for this car."
It's not the first time Hamlin has been fined for voicing his opinion. NASCAR privately fined him in 2010 for posts he made on Twitter about cautions.
At the time, NASCAR was secretly fining drivers for making disparaging comments about the racing product, and Hamlin's fine eventually became public as part of a push for the sanctioning body to be more transparent.
"I'm not going to say anything for the rest of the year, as long as it relates to competition," Hamlin said. "I mean, you can ask me how my daughter is, talk to me after wins about what have you, but as long as it relates to competition, I'm out from here on out. The down part is I feel like I've been a pretty good spokesman for them, and being positive when things aren't always positive. They just lost one small spokesman today, that's all."
It's already been a busy season for NASCAR discipline. Last month, the governing body suspended Nationwide Series driver Jeremy Clements indefinitely for violating its code of conduct with an apparently insensitive remark to an MTV blogger. NASCAR sent Clements to work with a sports diversity expert before he'll be allowed back in his car.
AP Auto Racing Writer Jenna Fryer contributed to this report.