Wow.....you would look forward to hills with all those different engines boted on...not so good for tailgaters though >
You can buy mini bolt on gas turbines. Bolt a few onto a rear bumper and light em up for hills. That would be ace. however i suspect the net result would be your bumper overtaking you on the hill.
650BHP Cosworth Formula 1 engine... sole purpose... to run the fuel pump! Puts things into perspective a bit doesn't it?