Does anyone have experience of using a roof rack, with its effect on MPG with and without bicycles? Particularly for the 2.0tdi 150 hatch.

Doesn't matter if you drive a superb diesel or any other car it will affect MPG.  More effects if the bikes are present and less of the bikes are not. 

 

Maybe if you are really concerned try driving very moderetly. 

 

Are you also taking luggage and people along? 

I do drive moderately. I'm familiar with affect of luggage and passenger but just wanted to hear of people's experience on roof rack and bicycle effect on MPG compared with identical conditions without. For example 60mpg normally, 55 with roof rack? Or is it more like 45?

Unfortunately I didn't really save/collect any actual data...  But I noticed quite a big difference when adding bikes and/or roof box made quite a bit of difference on both my previous Golf (SportWagen 1.4/140) and my current Superb (Estate 2.0/280). If I had to guess I would say it brought my mpg down by about 5-10mpg?

 

This article seems to back that up https://reviews.mtbr.com/that-roof-rack-is-destroying-your-fuel-economy

 

I guess it will also make quite  a big difference depending on if you are talking about one aero road bike or 3 fat bikes...

 

If you are worried about mpg and have a tow-bar it might be better get a tow-bar mounted rack?

I have one now and although I haven't done enough long trips to compare the mpg the lack of extra wind noise/whistling is great... 

Based on a 280 petrol estate, so maybe not too useful but my experience is a loss of 7-9mpg with 4 road bikes on the roof and 3-5mpg for the same 4 road bikes on a towbar rack. Bikes seem to be considerably worse on the roof compared to a roofbox, I guess as they to generate a lot of turbulence and also incidentally an awful noise!

 

If you can get towards a towbar rack then I'd recommend it. As well as the mpg, they are easier to load and don't risk car damage as much.

no MPG hit at all

 

https://eshop.skoda-auto.com/cz/en/b2c/interior-bicycle-holder

I've got a roof rack and 3 bike carriers which I keep on even when not carrying bikes.

 

I'd say the rack and bike carriers has a small effect on mpg, maybe a 1 or 2 reduction on average.  From 48 down to 46 or something like that.  Not worth taking the whole lot off and on again unless in the winter months perhaps.

When the bikes are on its a different story.  3 bikes on a decent trip drags the mpg down to low/mid 30's.