Service every 15 000km or ???

[onlybleeding]

When I puchased my IS250 the salesperson told me I need to service is every 15 000km, he didn't give me an 'or once a year' sort of thing.  

Now it's been about a year and I got an e-mail from the dealership saying I'm due for a service.  I've only done about 3000km, since I don't drive it all that much should I be looking at a yearly service?

If I go somewhere other than the Lexus dealership will I void my warranty?

[Spec]

Check the service book - it will have this 15,000 or every 12 months whichever comes sooner. 

Going to another service workshop (qualified only) will not void warranty unless it's extended warranty provided by a dealer subject to custom terms. As per law they can't void manufacturer's warranty on a new car if there was a service book maintenance done by a qualified mechanic/garage. depending on how old the car is though, it may affect resale value. 

[Teddinator]

Ok, so the OP really doesn't drive a lot at all....

Unfortunately you'll need to do a service in a certain interval as specified on the log book, even though you've driven nowhere near the 15,000 km.

This is to make sure certain components such as oil and brake fluid don't deteriorate too much by oxidation. This is just one of those things that just happens, whether you drive it or not.

And agree with Spec, as long as you take it to a trusted, qualified mechanic, you'll still have your manufacturer's warranty. Your dealer warranty (if you purchased extended warranty from them) will probably be voided.

[Lexus Nerd]

Spec and Teddinator gave the most important pointers.

How many km has your car travelled, in total, and how old is it?

If you bought the car brand new, then the first service at 12 months/15,000 km is free.

If your car is used, and the car has low km, but it's up for a relatively expensive service (e.g. 5 year service), talk it over with your Lexus dealer. They may recommend you get a basic service, including an oil and oil filter change - and defer the more expensive replacements until later - such as the fuel filter under the rear seat. Best of all, they'll still stamp your logbook.