I am 6'4" (definately the max for SmartCar) and the stock mirror was a huge blind spot for me.
Here is my mod.
I bought the replacement mirror at Kragen (I am sure you can find one at Pep Boys or at your local autoparts store). Also bought a Mirror Glue Kit (not pictured) which included a prep towelette and a small tube of glue. Some of the replacement mirrors came as a kit.
The stock mirror is removed from the windshield with a little upward force on the support stem.
The stem pops out of the mirror with a little bit of leverage.
Hacksaw (weekend warrior = lame tools) the stem just above the mounting area. The idea is we are creating a surface for the new mirror to mount to.
Using progressively finer sandpaper, sand the rough ridges where you cut until you have created a smooth flat surface. Then glue the mounting wedge to your newly created flat surface per the directions.
(sorry about the pic, small part poor detail but you can make out the lighter wedge from the darker surface that I created)
After allowing glue to set, per the directions, mount the new mirror to the wedge.
Then slide the assembly back onto stock wedge mounted to windshield.
Only driven with it for a few days and it makes all the difference. I can forsee eventually having to put a thin layer of foam tape on the top edge of mirror, but so far it doesn't move much and it's not hitting the overhead light area.
The angle out the back is a bit diminished (I can only see about 50-75 yards behind me with top up, with top down I can see as well as the stock (looking over the compressed top)) but I will trade lack of visibility out the front for a little less out the back.
Total Cost:
Mirror = $18.99
Glue Kit = $6.99
Under $30.00
About 1 hr of time for total install.
Hope this helps the tall Smarties