Big Fish Tuning

Tuning Testers

Fancy a free engine and/or gearbox tune? You’re on the right page. As we write files for vehicles across the globe we periodically will call for testers who can leave their vehicle with us so that we can test our new files are safe and suited for the wider market.

Please see below our current requirements for testers. If you meet the below criteria please do get in touch by calling us on 01642 918566, emailing, by using our Contact form on the website, or by sending us a message direct from our Social Media pages.

  • Mercedes E350

    Free engine and gearbox map for tuning testers!

    Vehicle must be aged between 2013-2016.

  • Mercedes C250

    Free engine and gearbox map for tuning testers!

    Vehicle must be aged between 2010-2016.

Terms and Conditions:

Tuning vehicles is a lot of fun but it isn’t without risk.

Whilst every precaution is taken by representatives of Big Fish Tuning to ensure incident free vehicle testing when using the Rolling Road, the following points need to be brought to your attention:

  1. It is the customer’s responsibility to ensure the oil and water levels have been checked prior to testing and that the car is in a suitable condition to go on the Rolling Road for power testing and tuning. Big Fish Tuning will keep the engine at an acceptable operating temperature using an additional cooling fan(s) if necessary.
  2. Engine and associated mechanical/electrical failures during Rolling Road Power Testing and Tuning are extremely rare so long as the engine is in good mechanical condition. The load imposed on the engine and transmission is no more to that of normal road use. A failure could occur for various reasons during Rolling Road power testing. Failures, for example are (but not limited to), turbocharger failure, supercharger failure, cam belt failure, due to wear or incorrect fitting, cylinder head gasket failure, engine overheating, due to faulty cooling system i.e. blocked radiator etc. contaminated engine oil or restricted oil filter, i.e. lack of maintenance.
  3. To perform a successful power output test on the rolling road the car will be subject to a low rpm in a high gear run from approximately 1500-2000rpm to the red line of the car. If you do not wish your car to perform multiple red line power runs, then please make this known to a staff member who will not run the car on a power run.
  4. You have ample opportunity to inspect your vehicle prior to it being strapped to the rolling road. You are welcome to check it in-between tests if you so wish.
  5. If you do not agree to these terms, no form, no run.

Insurance on Premise

During the hours of 9am until 4pm your vehicle will be covered under our insurance, outside of our working hours the vehicle will be covered under your own insurance though always secure inside our fully CCTVd compound to maximise security. If you’re in doubt as to whether your insurance covers your vehicle in another location overnight please get in touch with your provider to ensure cover.


  • How long will we need your vehicle?

    Typically around 1-2 working weeks initially and we may need you collect the vehicle to drive and test and report back to us at various stages. We will of course be as accommodating as we can to your own schedule.

  • Is it safe?

    We don’t call for testers until we believe that our files are safe for this stage of testing, however with all tuning comes risk as every car is different and every driver is different too. The good news is that your vehicle will be well cared for as we do for all customers and we’re fully to set up to deal with most contingencies here.

  • What do we do to ensure safety?

    We take full ECU backups before we start any works on your vehicle so if the files we’re testing aren’t quite right we can restore your vehicle to how it originally arrived. We’re also fully equipped with a dedicated ECU clean room and fully embedded 4wd dyno to ensure the safest possible testing environment.

  • What will be expected of me?

    Once we’re finished with your vehicle we’ll ask you to collect and drive the vehicle for a full week to test through what we’ve done. We will ask you to drive the vehicle for our week and then will arrange a phone call to catch up with you so that you can feed back to us any pros or cons you’ve experienced during that week. If there are any minor adjustments needed we will ask you to bring the vehicle back to us so that these changes can be updated in your vehicle.