by the same token, so are your parents :/ However, my opinion might not mean much since I don't know your parents any more than you know anything about Jaguars.
Modern Jaguars are fine cars, reliable as any other Ford, and arguably more reliable than some. The idea they are unreliable stems from the pre-Ford days. Every car can have an issue, not just Jaguars. Are they going to be more expensive to fix than a Mustang? Sure, the car itself costs quite a bit more, so one would assume the parts that go into it might cost more themselves. Doesn't really take a genius to grasp that concept. Cadillacs cost more to fix than Cavaliers, naturally. If low cost of maintenance and repairs are the primary factor in your purchasing decisions, you can stop looking at luxury sedans.
The opinion of a mechanic on the reliability of a kind of car is probably the last opinion one should ever solicit. How many perfectly funtioning examples is a mechanic ever likely to see? Maybe none? So from a mechanic's point of view, virtually every car is currently not working right. And we all know that is far from the truth. One would have to look at data on how many were sold vs. how many require more than routine service, and such data is not available to a mechanic working in a dealer shop. BTW, I've never met a mechanic that owned a car that was in good shape, something that makes me question the judgement of most mechanics when it comes to car recommendations
If someone claims they spend $600 on an oil change, I'd ask what else was done. Like brakes, tires, etc. Because unless you are an absolute idiot, WTF would you consent to paying that much for oil and a filter, plus a half hour labor? It certainly makes no sense to claim that's how much the poil and filter cost, when one can look in any auto parts store and see that 8 quarts of 5w30 and a filter won't run more than 50 bucks or so. Including labor, the job shouldn't cost more than $100 or so at the absolute max, unless other service is performed.
On this site, I always hear about problems with Mustangs. If you get a Mustang GT, definitely get an extended warrantee, as they seem to be the most unreliable car ever made. They are always breaking down, running roughly, making noises, and ruining heads. Total POS.