Thread: Wheel on Bonnet = Aerodynamic improvement

This document is amazing. Bumping for others to see who missed it in the past!

If you want to skip straight to the point, page 31 of PDF (which read page 21 on document page).

It's interesting I suppose, but a bit academic, the test was conducted at equivalent to 187km/hr, and the Reynolds number was fairly constant after 165 km/hr. It tells us what we already know; a roof rack increases fuel consumption, the actual percentage is not really accurate because most of us will rarely exceed 110 km/hr. It was interesting about the aerodynamic improvement with a spare wheel on the bonnet of the defender. It would not apply to many cars, because the defender has a fairly unique shape in modern times, and probably the poorest Cd of any car made in the last 25 -30 years. Volvo 2 series was often criticized for boxy (but practical) shape, & poor Cd. Volvos reasoning was Cd is a secondary importance to practicality for cars that spend most of their time below 100km/h. They must have got something right because it didn't stop them selling 2 series for 25 years. I notice on my tdi landy sitting on 95 -100kms hour with fully loaded 2.2 meter roof rack I still get less than 11 liters per 100km. I recently bought bonnet for carrying a spare wheel so I'm looking forward to an improvement.

Land Rover have always known that.
I was rereading an older LRO in the dunny, and came across an article by one of the Defender engineers who stated just that.
Regards Philip A

This thread has always cracked me up

Blokes who drive cars shaped like fridges worrying about aerodynamics