You might want to take it in to a shop, it could be your ball joint or a ty rod that might need to bo replaced. Also, if it's front wheel drive, the CV Joint may be wearing out, or it could be a wheel bearing (my car's wheel bearing went out and it was doing that too).
Check the air pressure in all tires.
balance or tires or brake rotors out of round front wheel drive cv axles
there are quite a few wheel bearing problems on these and sometimes differentials front and rear
the noise could be coming from either a bad wheel bearing or something wrong in front axle.
First check under the car below and in front of the radiator to be sure that ALL the plastic airdams are there. The radiator depends on the air flow directed to it. If all are there then the radiator is possilby restricted.
Check the bearing and wheel lugs.
Tire out of balance is the most common cause.
Only at low speeds, or worst at low speeds? Either way it's probably a bad front tire. Failing that, bad front wheel rim or front wheel rim not properly secured to the hub.
Are we talking about the front wheels or the rear? Have you checked your wheel bearings?
The mild clunking noise in the front end of your 2008 Smart Car at speeds of 30-40 mph could be due to several factors, such as worn suspension components, loose or damaged sway bar links, or issues with the CV joints. It's also possible that something is rattling or loose in the front end, such as a heat shield or wheel bearing. It's advisable to have a mechanic inspect the vehicle to accurately diagnose and address the issue. Ignoring such noises can lead to more significant problems over time.
Worn sterring and suspension parts. Put it on a rack and inspect all parts.
If its front wheel drive possibly an axle.