So you're going to buy a relay with 12V coil(s), you will need transistor(s) to switch the 12V coil current with the 3.3V esp-12e outputs. Correct?
Do you have a 5V power supply for the relay coils? How are you going to switch the 5V, 110 mA pulse required by the coils with 3.3V outputs? That relay is available in a 3V version but you still face the problem of switching a high current (probably around 180 mA at 3V) with a 12 mA rated output, even though it should be a short (10 mS) pulse?
If you go with the 12 volt version of the relay, you can drive it directly from two esp8266 outputs and the power is supplied by the vehicle. All that aside, if the device you're powering is on when the esp8266 is on, you can create a high side switch with p channel mosfet which would eliminate the need for the rather expensive relay. That's just a guess though as you've never explained what you're doing with the 8266 and the device being controlled by the relay.
Was trying to keep it short and simple but missed the details and was hoping to clarify as needed.
The IRF510 is a N channel device, it will not work as a high side switch. You need a p channel device wired something like this:
Switching ground on and off is another avenue I could pursue right?
Maybe yes, maybe no.Without knowing what you're switching on and off, a high side switch will always work because it opens the supply, like a relay would. A low side switch, effectively disconnecting the ground, may have other current paths to ground which will result in undesired current flow when the device is disconnected from its supply ground. It's all a matter of what you're trying to control which is still known only to yourself.
its a 12vdc 7W GPS device that Im controlling power to.
I downloaded fritz and drew up a diagram. Might be missing a diode protecting power to ground on the device and resistor on trigger to gate. Below should be an imgur link. The power for the nodemcu (esp-12e) will come from a usb to the car battery. For mosfet Ill either use a TIP120 or IRLZ44N . A link to the device Im using is below and I want to leave a 100ma capacity for adding a smaller device of similar power configuration.https://cradlepoint.com/products/cor-ibr1100-series#!specshttps://imgur.com/Ypryo6A