shit this thread was a good idea. Even though I used to have a 335i a few years ago neither of us had even considered a BMW as an option for him. I guess we were thinking of BMW's as being way beyond the limit we set, but a used 328 would work. Normally aspirated V-6 would provide decent power and fuel economy, but also not require premium fuel.
If your choosing between an Altima and a Mustang GT...the answer is ovbious in my opinion...MUSTANG GT!!! Have you considered a Nissan 350z or 370z? Those are some very nice coupes. You can find decked out 2010's for 30k and a decked out 350z for 20-25k.
That inline six has been around for a long time with BMW. Absolutely great motor, with enough power for anyones needs and reliability like no other. Mind you thats if you take "preventative" measures beyond an oil change and filling up the washer fluid, lmao.