Here is another way to look at it. Does this debt enable you to buy more car than you can really afford, or more car than you need? If so, it's bad debt.
Let's say you don't have the price of a new car, but you can buy a used car with the cash you have. You will have to repair the car occasionally, but this is generally a lot less than the payments on a new car. The value of your time may make sitting around waiting while your car is repaired very expensive (if, like me, you can earn money in fine grained amounts anywhere between 0 and 80 hours a week, and you don't get paid when you're at the mechanic's) in which case it's possible to argue that buying the new car saves you money overall. Debt incurred to save money overall can be good: compare your interest payments to the money you save. If you're ahead, great - and the fun or joy or showoff potential of your new car is simply gravy.
Now let's say you can afford a $10,000 car cash - there are new cars out there at this price - but you want a $30,000 car and you can afford the payments on it. If there was no such thing as borrowing you wouldn't be able to get the larger/flashier car, and some people suggest that this is bad debt because it is helping you to waste your money. You may be getting some benefit (such as being able to get to a job that's not served by public transit, or being able to buy a cheaper house that is further from your job, or saving time every day) from the first $10,000 of expense, but the remaining $20,000 is purely for fun or for showing off and shouldn't be spent. Certainly not by getting into debt. Well, that's a philosophical position, and it's one that may well lead to a secure retirement. Think about that and you may decide not to borrow and to buy the cheaper car.
Finally, let's say the cash you have on hand is enough to pay for the car you want, and you're just trying to decide whether you should take their cheap loan or not. Generally, if you don't take the cheap loan you can push the price down. So before you decide that you can earn more interest elsewhere than you're paying here, make sure you're not paying $500 more for the car than you need to. Since your loan is from a bank rather than the car dealership, this may not apply. In addition to the money your cash could earn, consider also liquidity. If you need to repair something on your house, or deal with other emergency expenditures, and your money is all locked up in your car, you may have to borrow at a much higher rate (as much as 20% if you go to credit cards and can't get it paid off the same month) which will wipe out all this careful math about how you should just buy the car and not pay that 1.5% interest.
More important than whether you borrow or not is not buying too much car. If the loan is letting you talk yourself into the more expensive car, I'd say it's a bad thing. Otherwise, it probably isn't.