My first attempt to create something...

I mean... You've just stretched the I series in blender.
If you make it work, as it should. You could make some sort of luxury class "L - series"
It would take a lot of work tho...
You would need to basically redo a lot of the Jbeam, Interrior, change some of the grilles and bumpers and possible add a V8.
It would be cool to see something like that, but as I said... It will be a lot of work, so for your first mod, in my opinion You should start by just making a reasonable V8 for the I series and then start playing around with Jbeam and when you get the feel for it start with this project.