Bob Lutz is one of Tesla's harshest critics. The outspoken former GM executive once said Tesla will go out of business by 2019 and that Elon Musk should step down as the company's CEO. Well, it's 2019 and Tesla just posted a profit in Q3, resulting in shares increasing by 14 percent. Lutz's latest target? The Tesla Model Y.

Never a man to mince his words, the former GM boss described the Model Y as "terminally ugly" during a recent interview with Autoline Network. "The Model Y, I think it is terminally ugly. I don't know who's going to buy that. It is another one of these humpback things like the Model X," he said.

Lutz continued his attack on the Model Y, complaining that it's "neither a sport utility nor a sedan, and to the extent it sells, I don't think it's going to break into a new segment." Tesla is confident the Model Y will overtake the Model 3 as the company's best selling model, but Lutz thinks the sales will be "largely substitutional to the Model 3's."

When the topic shifted to the Tesla Roadster and Semi, Lutz remained skeptical. "I don't think they are going to do that sports car anytime soon," he said. "They certainly are not going to do the Semi. If they did, they would be extremely foolish because that whole market is not enough to make a difference." He did, however, praise the Model 3's sales success and the company's recent profit the last quarter.

Lutz also believes that "clever PR and marketing" has given Tesla "more image value than an equivalent electric Chevrolet" and that the automaker is at the same stage as its competitors in terms of battery technology.

"I continue to believe that, and I keep repeating ad nauseam: when it comes to electrification technology, Tesla is at exactly the same place as everybody else, they use lithium-ion. The only reason why Tesla had more range was because they had a bigger battery."