Just a little detective work. Whether it's a crank but no start which means you probably ain't getting fuel or spark. If it's a no crank no start then it's probably a dead battery or a problem with anything in the starting system. But with cars these days it's a little more than just checking for 12 volts on the starter and if you didn't get no 12 volts you'd just condemn the ignition switch. Now before it even gets to the starter it has to go through a few modules first so you have to use a diagnostic scan tool to see if those modules are seeing the run/start signal and things like that. If you're in a situation where your scan tool won't communicate with the vehicle then you'd have to get to those modules and check all the power and grounds and sense wires with a multimeter and a connector pinout diagram and check off what you have and don't have.

Car batteries are made to last 4 - 7 years, so your battery in a 2010 is 4 - 5 years old . With winter upon us, I would just replace the battery now even if it has a little more life remaining, the really cold day your car won't start will be worth the cost of a new battery.

If the car wont crank over properly (slow or not at all) then that's probably a weak battery. If jumping it did start it, then the starter is OK. 4 years old, probably due for a new battery anyway.

But that has no effect on the engine once it's running. That's possibly the spark plugs, although there are other possible causes. If the plugs have done 80k miles, replace them anyway. Even if they aren't the problem, they will be soon.

It sounds like your car has more than one problem....

Anyone that asks a stupid question like this should never open the hood of a car! Tell me just how do you think a motor that won't crank (turn over) is going to have the starter motor effected by the spark plugs? The damn battery supplies the power to the starer motor.

Replace the plugs, it's cheap easy maintenance, just do it. The car has 80,000 miles on it and it's more than 4 years old, replace the battery.

TEST: With the truck just sitting in Park, engine running, check the voltage across the battery posts. If the voltage is like 14.5 volts, the alternator is working, so the battery is supect. If it reads like 12 volts, the alternator is NOT working.

if it cranks over at 400 rpm or better, that is a good sign on the battery.

a battery thats not fully charged will not allow the motor to function properly injecters,electronic ignition etc

Next time it doesn't start see if your headlights come on.

I left my car off for a day during cold winter. It wouldn't start so after a quick 2 minute jump start it was working.

Acceleration at higher speeds wasn't good and I heard that's indicative of spark plugs, but not starting up is battery. Also the horn wouldn't work for a bit.

I want to know so the car dealer doesn't rip me off. 2010 Mazda 3 80,000 miles so the spark plugs are technically up to be replaced but I hear some people wait til 100,000

so battery or spark plugs or could it be the starter?