I have a 1993 SC300 auto. Stock, except for 18" wheels. How much would I need to spend to make my car run a 12.0-12.5 sec 1/4 mile? What is the best way to go about it?

I was planning on selling my car, and leasing a 2001 E430. Want to get an idea of how much I would need to invest to make it enjoyable and forego the Merc.

Thanks.