No need to get your nose close. Use a voltmeter or multimeter (your new best friends). Then check the battery voltage—around 12.6V when off, above 13V when running (with engine on). And, while testing ...

The N52 is reliable, as far as BMW engines go. But that doesn't mean there aren't problems with it. Here are the years to watch out for in particular.

Learn more› By The Deals Team The Deals team hunts for and highlights only the best discounts on picks made by our editorial experts. As Prime Day winds down, we’ve stopped our up-to-the-minute ...