I have a 2012 Mustang V6 AND a 2004 Mazda 3. You should stop worrying and just drive like you would with your Mazda 3. Unless you are driving the Mustang like a jerk, you have more chance to encounter UNDERsteer than oversteer. Pushed too fast in a corner, you will feel the front end slide out as a warning. Just slow down by lifting your foot of the throttle a bit and you will get control back. If you hit the throttle too hard coming off a corner, the onboard nannies should help you out to keep the car on the road.
I have experienced both oversteer and understeer on track and never lost control. Worst i did on track was toasting my front brakes with repeated hard braking.... but really hard braking.
if you really want to learn how your car behaves, you should take an advanced driving class using your own car. May cost you a few hundred dollars, but it will be worth it. I have learned a lot about my Mustang driving it on a road course above the legal speed limit, so now i know how it reacts if pushed.
Canadian 2012 V6, MT, Perf.White Pony Package (3.31 gears). Koni Sport Shocks & Struts. Steeda Sport Springs w/HD Mounts, Route 66 SpeedShop 55D rear spring kit. Boss 302 Strut Tower Brace. BMR Adj PHB. BFG G-Force Sport Comp2. Pioneer TS-D6802R Front SPeakers, Clarion 80W/Ch Amp. JL Audio 8 Inch Sub And 175W Amp. GT500 Steering Wheel. 2012+ Tilting Headrests