A multimeter that covers 0/20V dc will do fine for a 12V car circuit.
A multimeter is the best tool for the job Set the voltage to 20 V. dc.
Virtually all automotive batteries nowadays are nominal " 12V " batteries, but will measure up to 13.6V when fully charged.
a voltmeter is used to measure voltage
Many can measure both - Vrms (AC) or DC voltage.
Any one using a voltage test instrument can measure charge differential voltage.
Ohm's Law applies where Voltage = Current x Resistance
Pounds
The unit of measure for voltage is volt. Ohm measures resistance.
A voltmeter would measure the voltage. If you measure the voltage drop over a known low resistance you get a kinda-sorta idea of the power available.
You don't. You need test equipment to measure voltage.
Odos measure the distance travelled and speedos measure speed at that movement
A voltmeter measures voltage in volts.