Is an old Class-A affordable to drive?

Affordable depends on your budget. As owner if a class C motorhome for 10 years, 30,000 miles of driving, the $9800 I spent for fuel was almost nothing compared to $40,000 depreciation, $48,000 lost investment income, $12,000 insurance, $7,000 storage fees, and $15,000 routine maintenance on the motorhome chassis.

If cost of fuel is your first concern, you are financially way over your head.