New Car Leasing website Project

Hi All,

I have a new project to create a new vehicle rental website in wordpress to effectively work in the same way as the site below (maybe a bit simpler)

http://www.apexrental.co.uk

My question is what plugins and knowledge will I need to produce a site that will allow the user to get an idea of price online given their choices of car / milage and preferred type of contract (Long Term Rental - Short Term Lease - Contract Hire). The clients current site is

http://www.octopus-leasing.co.uk

When the user has chosen their options they will then be pointed at an on line application to formally apply and send their details to my client for administration.

Is there even a decent responsive WP theme that will do all this for me but still allow for some design flexibility?

Your help is much appreciated.