My first car was a Peugeot 504 nilianua na 300k followed shortly after by a Subaru impreza yenye nilianua after disposing off the 504. By 2011, nilikuwa nimekulakula nikapanda bei kidogo. I used to cover a round journey of 10km daily to and fro. Kuhamisha job to south b cut the distance to about 5km round trip. Let us assume you stay in donholm and work in Industrial area or along thika road. With a 1500cc car, mafuta ya 300 imetosha which is almost the same as what you will pay kwa matatu. Contrary to popular belief, gari hupelekangi garage kila wiki so maintenance shouldn't really be an issue not unless if you drive like an animal or bought a really beat up car.
My point is, with determination and discipline, owning a car sii ngumu. OP akijikakamua na 500k, he is spoilt for choice of good condition vehicles like the second generation Rav4, Premio 240, Allion, NZE, second generation Honda CRV, Subaru impreza etc. All he has to do is patiently look around. Shida in kama yeye ni mtu wa numberplate. Hapo ndio atang'ang'ana kidogo.