My 2015 Nissan Altima has been an endless money pit and I've dropped over $3000 on repairs and maintenance and now it's making a noise when I start accelerating around 40-50km per hour but then it stops. I'm not sure what this noise could mean but it's somewhat of a grinding noise for a few seconds but then it stops on higher speeds. Would it be a transmission issue? I recently did a transmission flush and used the correct NS3 fluid and my mechanic recently replaced both front hub assemblies so im concerned now if I have to put more money into it. Has anyone else experienced this grinding noise that comes and goes when accelerating from a dead start? Other work I've done is change back rotars and breaks, spark plugs, new tires, had to replace transmission seal around axel (twice), and the rest was just the scheduled oil changes but this all added but to 3k in just 2 years of owing the vehicle. I got the car in 2019 from a used car dealership and it's 2015 model but it's annoying that I have to keep putting money into it. This never happened in my 2001 accord or my dad's 2001 corolla.