Consumer Reports - How Bike Racks Affect a Car's Fuel Economy

Coolbob

Well-Known Member
I was surprised at how much of an impact bike racks can have on fuel economy, even hitch mounted racks can make a notable difference.

 
No surprise to me. Some years ago I had a Volkswagen Passat wagon. Got close to 30mpg without a rack. With a roof rack and two bikes, the mpg dropped to about 24. Even the empty rack cost me about 2 mpg, so I took it off when I wasn't using it.
 
I leave my roof rack bars installed but 2% isn’t surprising given the horrible design. Mine are OEM BMW, but of Thule origin. Actually I’m not impressed with the design of any of Thule’s products after visiting the official Thule store here. The bars I have constantly hum and vibrate (helmholtz resonance technically speaking), and are about as aerodynamically efficient as a cut log 🪵 . It’s easy to see why they impart such a penalty on fuel consumption - the extruded aluminum causes them to use such a huge cross section that it induces a massive turbulence in the vehicles slipstream - twice at that. I could go on and on but to sum it up - Thule doesn’t care a s*it about aerodynamics. Thankfully I have a diesel and access to road tax free diesel fuel so it doesn’t bother me, but someone like the Greta zombie should crawl up Thule’s butt about climate change and carbon emissions.
 
Does not surprise me. I noticed a fair amount of difference in my overall mileage between letting my car reach the point wear the "need gas" light comes on compared to filling up before that point. Just carrying around less gas made a pretty big difference.
 
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