Its not to difficult to make your own decision.

1) Ask the delaer how much the first 3 services would cost if bought individually

2) Work out how much the service plan for those 3 services would cost you.

If 1 is greater than 2 buy the service plan, if 2 is greater than 1 don't.

But only buy a service plan if it is the manufacturers one. If you buy a dealer one and the cease trading you will loose your money. If the dealer proved himelf to be rubbish you cannot go elsewhere with the plan, if its a manufacturers plan you can go to any dealer.

We had a 3 year plan on the Leon. £11 a month for 34 months, total £374. Bought individually the services were over £450.

On the Skodas its £279 for a 2 year plan, the services are about £330 to buy individually.

But when we had the Kia the manufacturer plan was £24 a month for the first 4 services, £1152. The dealer quoted about £900 for the services so we did not but it despite his insistence it was great value. In actual fact we paid about £800 for the first 4 services including 2 MOT's but I did supply the oil after the frist service (he charged an incredible £63 for 5 litres). 15 litres of OEM spec oil cost me £62.

Start by checking the costs as Skidpan suggests.

I have a service plan on my Outlander that I know will save me money. Mazda's however don't seem such good value. The service plan for the MX-5 is £599. On the dealer's price list the first three services came to £702. I didn't buy the plan. The first service price had been quoted as £199. I rang a different Mazda dealer who quoted £147.

The plan won't include brake pads.

To add to the already excellent commentary as a owner of a Mazda car from new for over 12 years, I too would endorse checking both the prices AND reviews of as many Mazda main dealers as possible that are within reasonable reach, as servicing prices can vary by up to 15% in my experience, particularly if you live near a large city or upmarket area. Sadly the quality of the service departments at their dealers varies quite a bit and thus I'd go by reputation far more than price.

During the 3 year warranty period don't use an indie for servicing for the reasons already given, but a good one may be worth using for brake servicing and repairs as the vast majority of faults won't be covered by the warranty (as most, as I've discovered, are due to low use) and aren't cheap to fix at most main dealers. Some may price match indies if you're lucky, but again go on quality only - poor repairs or servicing will shorten the car's life, cost you more in the long run and can be more than an annoyance.

One thing to bear in mind (I looked last year to change my car and considered the CX-3) is that both the 16 and 18in tyres on this car and the 3 are quite uncommon and so are about 25% more expensive than the more common sizes like for my car, plus there's a lot less to choose from as well.