Why?

http://www.worldcarfans.com/110071527391/for-sale-1982-porsche-928-with-boeing-t-50-fire-breathing

 

Ha ha, 'why not' is probably the most obvious answer, especially if you happen to have an old Porsche and a helicoptor jet engine gathering dust in the corner of your garage.

I recall seeing (in a car mag in the early 90's) a jcb that someone had replaced most of the steel bodywork with fibreglass and fitted some massive V8 to. It could pull wheelies and blew flames out of its exhaust pipes. . Quite funny though.

 

But there are plenty of modified cars running petrol or even diesel that are more powerful!