As evidenced by the GenII's Cd of 0.26, IIRC, the overall design is pretty good all things
aero considered, due mostly to the iconic shape and Kammback I suppose.
That said, there is the opportunity to pick some aero 'low hanging fruit,' interestingly
enough, mostly from down low on the car.
Typically you can permanently block the upper grill, but it would be best to be able to
monitor coolant temps with a ScanGuage, etc. Foam pipe insulation is hardly noticeable
and costs ~$10. Lots of threads on this.
This list of other things that you might consider offers lots of flexibility in implementation.
These include:
* Lower grill block in colder weather
* Smooth wheel covers
* "Spats' behind front and rear wheels
* Beneath the rocker panels fore/aft air dams
* Full or partial rear wheel skirts
* Lower air dam at front
* Underbody panels at front and 'diffuser' at rear
* Antenna and right side mirror delete
* Windshield wiper cover
* Rear wiper delete
No one of these will produce sizable aero/MPG gains. I'd guess that taken all together,
and you're lucky, you might see Cd gains up to 5-10%, MPG gains of maybe 2.5-5 MPGs.
Which, with gas at $4/gal and an un-modded average FE of 50 MPG, could return gas
cost savings of ~ $37 - $75 across 10,000 miles. YMMV of course.
This isn't a terribly good Cd breakdown, but I can't find the better Volvo or Audi
breakdowns right now… or possibly ever again:
