A reserve driver is someone who will step in should something happen to one of the regular drivers whereas a simulator driver is a driver who does almost all their work on the simulator in order to gather set-up data and even test potential developments. A working example of this is at Mercedes. Should Lewis Hamilton or Nico Rosberg be unable to race; reserve driver Sam Bird will make the step up. However their simulator driver - who probably does more kilometres than anybody, albeit virtual - is Anthony Davidson.
Sahara Force India are currently in a unique situation where the line between the two roles has become a little blurred. We are the only team on the current F1 grid who do not have a reserve driver - we do however, have a simulator driver, Englishman James Rossiter.
Before the role of James is investigated, the question needs to be asked - why don't Sahara Force India have a reserve driver? Well, every team on the F1 grid looks for three things in a reserve driver; good technical feedback, money through sponsorship and reasonable pace. Considering that all drivers in contention for an F1 seat, even if it is just a reserve driver role, possess a certain level of technical feedback and pace through experience - these can be ignored for now meaning that the key consideration is money through sponsorship. It is quite possible that the team can not find anyone with sponsorship to take the role, however given the determination of modern day drivers - that is highly unlikely, they'd find some money from somewhere. So why is the position not taken?
The reason for the team not having a reserve driver, i believe, is also the reason for the team's success this season. Quite simply, if they were to hire a reserve driver, there would have to be a provision in the contract for a minimum amount of track time, and the team want to focus all their efforts on their main drivers in order to give them the best chance of achieving strong finishes in the race. They will not be gaining as much income through sponsorship as they could with this method - but don't forget there are young driver tests where they may receive some money from budding drivers wanting a run-out.
However, if the team focussing all efforts on the main drivers is true, why was it recently announced that the simulator driver, James Rossiter, will be getting a run-out in FP1 at the British GP. There are two potential reasons for this. The first reason would be to check that the simulator is providing reliable data that is realistic - this would be checked by comparing James' lap times on-track to the lap times on the simulator in similar track conditions. The second reason is simply that it is James' home race and they are kindly letting him have some track time; this will be a very special moment for James, as he said on twitter: "Seriously looking forward to driving the F1 car in Free practice for my home race!".
Thanks for reading,