RE: "Yesterday was the type day where it was sunny one moment, cloudy, partially sunny and then full blown sun again for 2 minutes."
This is the type of conditions where, over the past few years, I've used AUTO ISO in Manual exposure mode on my Nikons...works well, keeps me at the desired shutter speed and desired f/stop, and moves the ISO up or down as needed to arrive at the correct exposure that I myself, pre-selected. With the perfortmance of newer-generation sernsors in good light outdoors, AUTO ISO shooting has become very viable among a number of different genres; bird in flight people use it a lot, I love it at the beach, where back-light,side-light,and front-light conditions can change withing a second or two, simply depending on what angle you've got the camera pointed.
BTW, I enjoy seeing torque wronkles in big drag slicks!
When you have to shoot in constantly-changing lighting or background conditions, AUTO ISO in Manual shooting modecan maintain the right speed and f/stop faster than a human can even think! That's what I love about it. If the pictures look too dark, just click in a bit of Plus-Exposure Compensation, if they are consistently too bright, then dial in a bit of Minus Exposure Compoensation.