My exact setup 
JB4 and PSS4S
You can run a custom tune on a lease car? That seems incredibly risky, right?
Really nice car and price. Love that colour
Just have to remove it before visiting a dealership.
This my 3rd tuned 3 series-never had a single issue.
My 328i with a piggyback ecu is probably under 5 sec. As mentioned above it is plug and play so pretty easy to remove.
340i. 4.6
Scatpack. 4.4
A4. 5.0
Gulia. 5.1
Mkz 3.0t. 4.9
Mustang gt
Etc
Iāll echo what most have said here already, anything turbocharged with a tune will get you there and easily reversible when you need service.
If only RS7s were cheap to lease 
Has anyone mentioned the Infiniti Q50 red sport??
OP doesnāt want to go Infiniti again
Alfa Giulia will probably feel faster and more visceral than most, due to the height/size of the car and driving dynamics, not sure about reliability yet though.
I am picking up my new 2018 540e today in NJ and was able to get a sub-$500/month (not including taxes and $0 down)? So think a 5 series could be workable if you do the work.
Did you mean 530e?
540e doesnāt exist and a 530e isnāt a fast car
Yes, I meant 530eā¦fat fingers. Oh I saw the 5 series mentioned in the original post and thought the e and the gas would be same in speed, my bad!
I saw a Hellcat on special: 36/10, $3500 drive off, $680/mo plus tax. I know thatās over budgetā¦but itās a legit Hellcat.
V6 ftype + tune and pulley = 450 hp
Low 4s 0-60 looks amazing and drives way better than any other option.
Could add Jag XE and XF to the list as well.
Hellcats have really strong residuals at %65 for 36/10 and it doesnāt really get much faster than those. $600 range is possible if you are not picky about options.
Might be lucky in getting a hellcat in the $500 range if itās a demo or loaner. Not sure if they do those.
Would definitely add Jaguar XE 3.0T (I think? didnt checkā¦)
Ford Fusion Sport (Check it out, itās a sleeper.)