I had the OEM aero-bits installed on my 2017 Golf Sportscombi/Variant/Estate/Sportswagen upon delivery in August 2016. (Most recently posted here: https://golfmk7.com/forums/index.php?threads/how-to-retro-fit-skid-trays-aerodynamic-under-trays-stone-guards-to-a-mk7-golf.320687/post-6659942)
My car is a Swedish-spec GT with DCC, so the suspension, brakes, and ride height match the non-PP GTI. The engine is the 1.4l TSI, 150hp, with a 6-speed manual. I fill it with the highest octane fuel that is available locally (Shell V-Power, aka Nitro in other places, >98 octane) to get a bit of extra power without the need for mechanical or electronic enhancement.
Since taking delivery we have driven just over 70 000 km (43 500 miles) using just over 4521 liters (1194 US gallons, 994 UK gallons) of fuel. Our average fuel economy is 6.48 liters per 100 km (36.3 US MPG, 43.6 UK MPG). I am very pleased with the highway economy in particular. One one day last summer I drove 287 mostly highway km including extended cruising at about 140 km/h (87 MPH) while burning only 16.94 liters of fuel, which worked out to 5.9 liters per 100 km (39.8 US MPG, 47.8 UK MPG).
As the aero-bits have been mounted since day one I can make no A/B comparisons regarding relative fuel economy, noise levels, stability at speed, or top speed, but I would like to think that having them does some good in all of those respects. I can report that everything remains solidly mounted after several snowy winters and a short speed burst that was slightly faster than the one reported by golfdave (but not as fast as the track speeds noted by others!), and nothing has proven to be troublesome through 3 factory service intervals and yearly safety inspections.
I remain very pleased with the car, and I plan to hang on to it for a while yet, at least until VW rolls out the Mk.8 GTE wagon with 242 hp! Hopefully golfdave will have an updated guide for that vehicle by the time I am ready to take delivery!
Very good report!...….
As you know I have the 140PS version of your car, & use the same Shell fuel.
I have seen 52mpg (UK) (5.4lts/100km) on a long motorway journey (320miles/514km).....& now regularly see 46mpg (UK) (6.1lts/100km) on 36mile trips.
As for the Mk8 Golf, VW have been watching my threads I think!. The new 2019-> Polo & Tiguan both have fully covered undersides! I had a new Polo as a courtesy car whilst I had a new timing belt fitted to mine. I jacked the car up & looked underneath!!!..WOW everything is covered, suspension, engine bay, subframe, the whole lot!. Same with the Tiguan that I have seen in pictures.
So I recon the whole underside of the Mk8 Golf will be the same!
Anyway I'll be keeping my Mk7 for hopefully another 10yrs!....