Have you ever seen the screen on a Prius in the sun. The answer is no, all you can see in the sun is glare. A friend of mine has a 2010 MB 550 its better but by no means transflective. I think it's better because of the placement, the windows have high end tint, and it is slightly crisper, but is is a $100,000 car so it should be better compared to the Prius. I dont think the car MFG have it all figured out yet either.
Here are some links to pics that I took this morning. I tried to match the angles the best I could with the 2 monitors. The image on the screen is the same as is the brightness and contrast ratio. The pics are unedited. I left them big intentionally. I tried to get glare off of the screen with a flash and I couldn't. The monitors in the pics are a standard 4 wire 250 nit Lilliput 669 HDMI monitor compared to our new enhanced high brightness 450 nit 4 wire Transflective Optically Bonded model.
Here is the stock with direct sun hitting the upper right corner.
and the TFE comparison
These 2 pics were taken in direct sunlight but the sun was not directly hitting the screen.