Thinking about a new car but need advice?

So, I have a 2008 Acura TSX and love the car, but sometimes I feel like there's better options. I'm looking at Infiniti G35s and Lexus IS250s ranging between 2006-2008, and costing under $30,000. Is there some way that I could basically get one of those cars without spending or losing alot of money? My car is on a 5 year payment plan and about $13,000 is paid off, about $10,000 left, so is there ANY way I could have a different car but go on as normal? Hope this makes sense.