So some basic algebra

**Units**
distance in miles

time in hrs elapsed

h = heater kwh average

**Speed vs time equivalent equations**
speed = distance / time

speed*time = distance

time = distance/speed

**Equation for speed/power**
Wh/mile = MPH^2 / 30 + MPH * 5/6 + 120

Wh = time*(Wh per mile equation)

Wh = distance/speed*(Wh per mile equation)

**Equation for heater**
heater kWh = Ht

heater kWh = Ht

heater kWh = H*distance/speed = H*D/MPH

**Total equation for watts used (adding above equations together):**
D/MPH*(MPH^2 / 30 + MPH * 5/6 + 120) + H*D/MPH

or

(D/x)*(x^2 / 30 + x * 5/6 + 120 + H)

**Step 2: Add distance and heater constants**
In this case H=5kwh, D=60 miles

D*x/30 + D + (5/6+120)*D/x + H*D/x

2x + 60 + (5/6+120)*60/x + 5*60/x

**Step 3: Graph and Find Min**
Best Graphing Calculator Online (Easy-to-use & Free)
In this case, min is 61 MPH for 294 kWh.

Now applied to 200 M, the value goes up slightly to 65.64.

For 10 miles, about 39.3 MPH.

__This is only as accurate as the math above and the input constants and power/MPH equation__, but you can re-apply and fix/improve using the same basic technique.

The heater constant will always be changing, and also

**it was made up by the OP** for example purposes, so these charts attempt to refer to a heater that uses 5,000 W average.

Also, removing the heater from the equation only drops by 10 mph, whereas some say lower is better,

**so the power input equation is probably wrong**.

But this is approximately how the math could be done.

**Power equation taken from this user forum post**
Table of energy consumption vs. speed | Tesla