Top Gear Overdrive features several bonus cars which can be unlocked by advancing through the season:

The Weinermobile
Nintendo Power Concept Car
The N-Logo
Taco
Museum Artifact
Circuit Cart with donkees
These are the regular cars and their prices:

Type Cost
EC 18,000
YD 30,000
CA 55,000
HM 145,000
PO 185,000
FO 240,000
JS 290,000
MC 350,000