Common Vehicle used in Madagascar

You will see all brands of cars here.  Some American Fords, plenty of Japanese cars and many that are 4x4 which I think is not so important unless you plan to go off road. Even the dirt roads can be driven with a regular sedan type car.
The most widely driven car is the Renault and the Peugeot,and these cars are easy to fix by many garages and for low cost and usually you can be fixed within a day.  Not much computer work to be done in these cars with older models. If you have a chauffeur then he can double as your mechanic on a Renault and Peugeot as they are easy to fix.   
I have notice that with the increase of traffic that people are buying smaller cars and not 4x4s either.  4x4s used to be a status symbol years ago but not so much anymore.
Also Scooters are on the rise and you will see many scooters now where as I hardly saw even one 5 years ago.  I got myself one because of the traffic congestion, ease of care and easy on gas of course- rain is another story.

Noted

I was intending to get a New Land Cruiser. Thought the spare parts might be cheaper.

I have seen some of those as well on the road, and very nice indeed- not sure about spare parts- you might like to google that further or call some auto parts suppliers.  Not sure where you are located but if you are on the West coast for example you might like to have Air Conditioning, plenty hot and humid.