Petrol

I found the tunit very easy to install and despite some sceptisism on my part about an 'add on box' as opposed to an ECU reprogramme, I am impressed with the unit. I had a motorway journey planned from North Wales to London in my Nissan Navara towing a Fifth Wheel and decided to drive half way, stay overnight, install the tunit the next morning and compare.

As both halves of the journey were predominantly motorway and dual carriageway, carried out in similar weather conditions (dry and blustery) and I set the cruise control to the same setting (68 mph) I think these are fairly accurate results. The first half of the journey without the Tunit the automatic gearbox seamed to be changing gear a fair bit and I achieved an average consumption of 13.1 mpg off the trip computer. The second half of the journey with the Tunit installed seamed to be more relaxed with the gearbox only changing occasionally and the vehicle able to hold it's speed more consistently, fuel consumption was 18.2 mpg, a significant improvement. I have not compared the performance when not towing in an objective manner, but subjectively it now feels more like a sports car rather than a big truck and I am averaging 32 to 34 mpg, so both performance and economy have improved.

I have had two vehicles with remapped ECUs - an Audi A3 2.0 TDI 140 PS and a Fiat Ducato 2.8 Motorhome. Both had impressive hikes in performance and improved fuel consumption, but not to the scale of the tunit, I have been changed from a sceptic to a convert.

Thanks for your help when making this decision it is not one that I will regret as I will recover the cost very quickly.

Paul, BMW 335d